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VAV or CAV-DTC Control

1. Clg Control Q Setpoint 1 40 100 F Temperatures Q Dead Band 0 10 F O Method Nearest 1 Nearest Average 0 0 Min EWT 55 F 1 e 20 100 F Temperatures Min Spt 55 F 1 0 100 F 70 F 1 0 100 F No Reset 1 Airflow External ar BEE EC Space EH NoRst J Min Spt r awer Ir Max Spt ne 1 ower TI Min Spt 76 1 om TI Max Spt 1 0 100 Stg Timer i 1 5 60 Min ModLimit 1 1 60 F O Wait Time 1 1 60 Sec O Max Step 1 1 60 Sec O PATime 1 0 255 Sec 14 O Ho Control 3 Setpoint 100 F 1 40 140 F Temperatures Supply Air Dead Band 1 F 1 0 10 F O Fan On Htg No 1 Yes No Max OAT 60 F 1 0 100 F 2 Temperatures Outdr Air Min Spt 60 F 1 40 120 F Max Spt 120 F 1 40 120 F O Reset No Reset 1 Airflow External OAT Return Space No Reset Min Spt 69 F 1 0 100 F Max Spt 64 F 1 0 100 F Stg Timer 5 Min 1 2 60 Min Mod Limit 60 F 1 1 60 F Wait Time 30 Sec 1 1 60 Sec Max Step 1 1 60 Sec 9 PATime 1 0 255 Sec 15 Alarm Limits Hi Supp
2. NMP Sched No N A N A 1 32 Sun 00 00 00 00 0 23 0 59 0 23 0 59 Mon 00 00 00 00 Same as Sunday Tue 00 00 00 00 Same as Sunday Wed 00 00 00 00 Same as Sunday Thu 00 00 00 00 Same as Sunday Fri 00 00 00 00 Same as Sunday Sat 00 00 00 00 Same as Sunday 00 00 00 00 Same as Sunday 0 255 Min N A Jan Dec 0 31 1 5 Days N A Jan Dec 0 31 1 5 Days N A Jan Dec 0 31 1 5 Days N A Jan Dec 1 5 Days pu e 1 CI Factor 25 Min Holiday Date 1 Date Dec 25 1 Dur 1 Day s 82 Date N A 0 2 Dur 1 Day s 3 Date N A O 3 Dur 1 Day s 4 Date N A 0 4 Dur 5 Date 5 Dur 1 Day s 6 Date N A 0 6 Dur 1 Day s 7 Date N A 0 7 Dur 1 Day s 8 Date N A 0 8 Dur 1 Day s 9 Date N A 0 9 Dur 1 Day s 10Date N A 0 10Dur 1 Day s 10Date N A O 10Dur 1 Day s 12Date N A 0 12Dur 1 Day s 13Date N A 0 13Dur 1 Day s 14Date N A 0 14Dur 1 Day s 23 Optimal Start Opt Start Off Off On Auto Update Yes Yes No Ht Rate 0 400 F M O 1 000 F M Heat OAT 35 F 100 155 F Ht Factor 25 Min 0 255 Min CI Rate 0 400 F M 0 1 000 F M Cool OAT 85 F 100 155 F Y ejen aja n N A Jan Dec N A Jan Dec 0 31 1 5 Days N A Jan Dec 0 31 1 5 Days N A Ja
3. 13 Clg Control Page 26 OM 123 You can choose the source of the Control Temperature from among the following selections Space temperature sensor Return temperature sensor Outdoor Air temperature sensor Mixed Air Temperature sensor SAT for heat on 100 OA units Setpoints and Dead Bands To determine whether to activate the unit s cooling or heat ing equipment the controller compares the Control Temperature with separate cooling and heating enable set points When the Control Temperature is above the cooling setpoint by more than the cooling dead band and SAT gt SAT Clg Setpoint SAT dead band the cooling equipment is acti vated and the operating state changes to a cooling state Economizer Cooling Unoccupied Economizer or gt Unoccupied Cooling When the Control Temperature is below the heating setpoint by more than the heating dead band and SAT lt SAT Htg Setpoint dead band the factory installed heating equipment if any is activated and the operating state changes to a heating state Morning Warm up Heating or Unoccupied Heating Once the unit s cooling or heating equipment is activated it will remain operational until the cooling and heating load is satisfied For more information see the following sections that apply to the cooling and heating equipment your unit is equipped with Note that cooling and heating can never occur simulta neously because the controller w
4. 6 hr mn mm dd yy Prev Alarm Alarm Message Same as Curr Alarm O hr mn mm dd yy Comp Alarms Notes 1 1 2 2 3 3 4 4 5 5 O hr mn mm dd yy 6 6 7 7 8 8 C lear Bufferz 1 Alarm Message No No High Pressure Water Regulating Valve Frost Low Pressure Motor Protection 2 Alarm Message Same as 1 3 Alarm Message Same as 1 st4 Alarm Message Same as 1 5 Alarm Message Same as 1 ite Alarm Message 1 Not available for units with chilled water Same as 1 OM 123 Page 15 Operator s Guide The following Operator s Guide sections provide informa tion on the day to day operation of the Self contained Air Conditioning Unit Controller They tell you how to perform such common tasks as scheduling displaying and clearing alarms and setting the controller for manual operation For detailed information on the control processes and their programmable setpoints and parameters see the Description of Operation and MicroTech Control Features portions of this manual Determining Unit Status The MicroTech Self contained Air Conditioning Unit Controller provides a variety of information that you can use to determine the overall status of the unit At the keypad dis play most of this inf
5. tem Name pt Pst Heat Timer On cooling only units or units with staged heating equipment the unit controller will enter the Post Heat operating state after leaving the Recirculate Heating or Unoccupied Heating state During Post Heat the VAV Heat output remains open while the supply fan inlet vanes are forced to a minimum position 17 open fixed By forcing the supply vanes to their minimum position before the VAV Heat output closes Post Heat eliminates the possibility of duct overpres surization because the duct pressure drops before the VAV boxes can close off The Post Heat state lasts until either the supply fan inlet vanes reach their minimum position or the post heat timer expires whichever happens first The post heat timer s default setting is three minutes It starts timing when the con troller enters Post Heat When Post Heat is over normal duct static pressure contro will resume Unoccupied Control Heating Night Setback Programmable Parameters Keypad Display ID Parameter Menu em Name 16 Unocc Htg Clg Unocc Htg Clg Night Setback Setpoint Night Setback Differential Heating Spt 55 F Htg Diff 3 F If a zone temperature sensor is connected to the controller night setback heating control is available regardless of whether the heating equipment is factory equipped or field installed in the ductwork Following is a description of oper ation If the zone t
6. CATEGORY i Menu Structure The keypad accessible information in the MicroTech con troller is organized in a menu structure to provide quick access As shown in Figure 2 this structure is divided into three levels categories menus and items The category which is the highest level in the structure can be Status Control or Alarm The name of each category describes the basic purpose of the menus it contains Complete infor mation on the contents of each menu is included in the fol lowing VAV and CAV DTC Menu Tables section Status Category Menus in the Status category contain information about the current operating conditions in the unit The fields in these menu items provide status information only and cannot be changed with the keypad The Status category menus are summarized in Table 2 Control Category Menus in the Control category contain setpoints and para meters that define how the unit operates After the password is entered most fields in these menu items can be changed with the keypad The Control category menus are summa rized in Table 3 Alarm Category Menus in the Alarm category contain current and previous alarm information The Alarm category menus are summa rized in Table 4 Figure 2 Keypad Accessible Menu Structure Category Menu Item Display Format The information stored in the controller s menu structure can be viewed on the 2 line
7. Unoccupied Heating The Unoccupied Heating operating state occurs when heat ing is required to satisfy the night setback setpoint during unoccupied periods When it occurs Unoccupied Heating always follows the Start up Initialization and Recirculate operating states During Unoccupied Heating the outside air dampers are closed and the occupied output is closed The VAV Heat output is open and normal duct static pressure control is maintained For more information see the Unoccupied Control sec tion Sequence Charts Operating states and the transitions between them help to describe the unit s sequences of operation The following sequence charts show every possible operating state transi tion that can occur as a result of normal temperature and pressure control Figure 6 is for units with return air and Figure 7 is for units with 10096 outside air cooling with mod ulating heat Depending on the unit options some operating states may not apply Figure 6 Sequence Chart for Return Air Units Any Other State ue e ott Be SS SE Start Initial Morning Warmup _ _ _ _ __ _ n gt Recirculate Unoccupied Heat N MET Ed a eer Post Heat ea Heating Fan On Heating Nel ot A Cooling Economizer Unocc Economizer Figure 7 Sequence Chart for 100 Outside Air Units EENS Any Other State Heating Post Heat OM 123 Page 25 Star
8. Electric shock and moving machinery hazard Can cause severe personal injury or death When the unit is in the Off operating state power is not removed from the unit controller or components Lock power off by means of the unit disconnect switch before servicing line voltage equipment or entering the unit Control Mode Programmable Parameters Keypad Display ID Control Mode You can set up the unit for automatic or manual operation by selecting the unit s contro mode with the Control Mode para meter Following are descriptions of the seven possible con trol modes OM 123 Page 17 Off Manual The Off Manual control mode will place the unit into the Off Manual operating state see warning above In the Off state the unit is shut down For more information on operating states see the Operating States and Sequences section of this manual Caution The Off Manual control mode can be overrid den by an operator at a remote PC or RMC Panel if any To eliminate this risk disconnect unit power or disconnect the communications cable from MCB1 This risk can also be eliminated by placing the unit into the Shutdown service mode see below Auto The Auto control mode allows the unit to operate automati cally This means that the unit will start and stop according to any external on off switch scheduling tenant override operator override or unoccupied temperature control com mands Once running
9. o Enthalpy Econ Yes No Yes 6 Economizer Q Changeover 0 100 F 6 Economizer 75 F EWT Diff 0 10 F 3 F Dead Band 0 10 F 1 F 19 Head Pressure gt 1 mod limite sop 3 1 9 watumie tose 3 zese lt 1 Ya Max Step 10 Sec 18 Economizer Mod Limit Wait Time 30Sec 1 1 60sec Max Step 30 Sec 1 1 608e0 A PA Time 60Sec 1 0 255Sec Ji E 1 60 F Hee 60 F 1 140 210 psi 10 Misc Status 1 E 1 60 Sec Control None None Rel Hum DewPt Enabled Occupied Always Occupied Sensor Return Return Space Timer 10 Min 1 60 Min Humidity Spt ___ 50 0 99 10 Misc Status Humidity Db 0 10 2 DewPt Spt 10 Misc Status 50 F DewPt DB zr Min Stages O Humidity Ctrl Max Stages Initial 120 255 Sec Recirc 1 60 Min Airflow 0 Sec 5 Min Bypass 3 10 Min Ovrde Inc hr mn sc 1 21 0 59 0 59 o Page 12 OM 123 day mm dd yy Sun Sat 1 12 1 31 Table 3 Control Menus Cont d AA EEE EE Default Shown en hem Schedule Override 0 00 Hr 0 00 5 00 Hr
10. Alarm The first item of menu 26 is also displayed It probably shows No Active Alarms Assume that a fault alarm exists 2 Press clear in the Action key group This clears the alarm and returns the unit to normal operation Modifying a Schedule In this exercise assume that a change in building occupan cy requires the self contained unit to run from 12 30 a m to 5 00 p m on Saturday Currently the unit is scheduled to be shut down on Saturday Using the following procedure you will change this schedule accordingly This procedure assumes that the password has previously been entered and the 15 minute authorization timer has not expired 1 Press alarms in the Category key group The first menu of the Alarm category is displayed This is menu 26 Curr Alarm 2 Press prev in the Menu key group four times Menu 22 Schedule is displayed The first item of this menu Override is also displayed Note that you could have started at the beginning of the Control category of menus and stepped forward to menu 22 by using the next key but it would have taken longer 3 Press prev in the Item key group three times This makes use of the wrap around capability Menu item Sat is displayed The default start stop schedule of 00 00 00 00 should also be displayed Each of the four sets of zeros is an adjustable field start hour start minute stop hour and stop minute Note that you could have stepped for ward t
11. Decr Key When the decr key is pressed the entry in the item s selected field will change to the next lower value or previous available selection The field being edited will flash until the enter or clear key is pressed Enter Key When the enter key is pressed the entry in the item s selected field will be locked in If the selected item has one field pressing enter also completes the edit If the selected item has more than one field pressing enter also makes the next field available for editing with the incr and decr keys If no change is desired press enter until the desired field is flashing or the edit is complete It is possible to initiate an edit of a multi field item by pressing the enter key In this instance the first field would be left unchanged and the second field would be available for editing Page 6 OM 123 Clear Key The clear key is used to clear alarms and edit ed flashing fields When menu 26 Curr Alarm is in the display pressing clear will clear the current alarm When an item field is being edited pressing clear will restore the field s previous entry and end the edit Keypad Display Exercises Following are three exercises that will guide you through some typical keypad operations Note that often there is more than one way to perform an operation For example you can use the Menu group keys with or without the option al Category group keys to quickly f nd the menu you want to display Ch
12. S2 is in the Auto mode The unit will stop when the timer expires Like the Override Increment parameter the Override Timer can be set for any amount of time up to 5 hours in 15 minute increments The control mode menu 11 must be set to Auto to use the operator override feature Note If the Override Timer s remaining time is larger than the Override Increment pressing the tenant override button on the space sensor will have no effect If the Override Timer s remaining time is less than the Override Increment pressing the tenant override button will reset the Override Timer to the Override Increment Fast Timers Programmable Parameters Keypad Display ID wem Parameter Name Timers Normal Operation Timing Flag If desired you can temporarily speed up most of the con troller s internal timers by using the Operation Timing Flag When set to Fast the Operation Timing Flag will temporar ily reset the settings for the following timers to 20 seconds Start up initialization timer Recirculate timer Low supply temperature alarm delay timer Cooling interstage timer Heating interstage timer The timer settings will return to normal if 1 the Operation Timing Flag is set to Normal or 2 no keypad action occurs for 15 minutes The purposes of these timers are described in the Description of Operation portion of this manual Caution This fast timers feature is meant to be used only b
13. after unit start up The mod limit parameter s units are the same as the controlled variable s temperature pressure or position Dead Band The dead band sets a range in which no control action will be taken If the controlled variable is within the dead band range the actuator will hold its position Note that the dead band parameter s value is added to and subtracted from the setpoint to determine the dead band range For example if the dead band is 3 F and the setpoint is 55 F no control action will occur when the controlled variable is between 51 F and 59 F The dead band parameter s units are the same as the controlled variable s temperature pressure or position OM 123 Page 47 Figure 18 Typical Step and Wait Operating Sequence Slee Sege Se a a a 2 I U Mod Limit em m emm pm ger em ml een e em aa om gn aaa em em gg aa em EE em em em em em e E 2 2 Dead Band as i EEDE w em eg wj r or mm wm e em mm mm wg pm mm jika wen em mm mm em eg em zm m jaw emm en on em zen em e Jun o zen ep em pes mm e EE 3 EI Ki Setpoint 60 of s l ae e cm occa Mod Limit o 9 lt LI LI SS SS a a l 2 RE La Mun e mu a Geet a wm e Max Step Max Step l Max Step D b Step Period 1 Step Period 0 OBAS Wait Period Wait Period i Step Period oBA4 E tas Wait Period 0 La ls 60 of Max Step Wait Time Wait Time Time Typical Oper
14. is enabled Then the Control Temperature begins to drop When the Control Temperature falls below the cooling enable setpoint minus the cooling dead band Point B all cooling is disabled Since heating is also disabled the fans will simply circulate air When the Control Temperature drops to the heating enable setpoint minus the heating dead band Point C heating is enabled one stage heating is also activated Then the Control Temperature begins to rise When the Control Temperature rises above the heating enable setpoint plus the heating dead band Point D heating is again dis abled Figure 8 Typical Heat Cool Changeover Operating Sequence Cooling Dead Band A EN COCO VIV VV VV Y VN VV Cooling Setpoint DEET AVAVAVAVA VAVAVAVAVAVASA S AVAVAVAVANAN DAA Heating and Disabled e Heating Setpoint Control Temperature DIA A Heating Dead Band Multiple Unit Applications Common temperature control for multiple unit applications is available with the optional Remote Monitoring and Control RMC Panel To use this control strategy you must select Network as the Control Temperature source at each unit controller in the group In addition you must set each unit controller s cooling and heating setpoints and dead bands so that they match the others in the group For more infor mation see Bulletin No OM 121 MicroTech Remote Monitoring and Control Panel Economizer Waterside or Airside T
15. the unit will act as required to main tain its temperature and pressure control setpoints Occupied The Occupied control mode causes the unit to run continu ously in the occupied mode Any scheduling commands are prevented from shutting down the unit Both heating and cooling are allowed to operate as necessary to maintain the temperature control setpoints Occ Cool Only The Occ Cool Only control mode causes the unit to run con tinuously in the occupied mode Any scheduling commands are prevented from shutting down the unit Cooling is allowed to operate as necessary to maintain the temperature control setpoints Heating is disabled Occ Heat Only The Occ Heat Only contro mode causes the unit to run con tinuously in the occupied mode Any scheduling commands are prevented from shutting down the unit Heating is allowed to operate as necessary to maintain the temperature control setpoints Cooling is disabled Occ Fan Only The Occ Fan Only control mode causes the unit to run con tinuously in the occupied mode Any scheduling commands are prevented from shutting down the unit Both heating and cooling are disabled Calibrate The Calibrate control mode automatically calibrates the posi tion feedback pot on the economizer valve outdoor air damper and VIV actuators It also calibrates ell the unit s static pressure transducers Following is a description of the Calibrate procedure After Calibrate is selected the controlle
16. 4 20 mA signal controls the current discharge air cooling setpoint The reset sensor minimum and maximum cooling setpoints are not used This reset action is illustrated in Figure 12 When the external signal is 1 VDC not adjustable the current discharge air cooling setpoint will equal the minimum discharge air cooling setpoint Min Spt Point A in Figure 12 exemplifies this When the external signal is 5 VDC not adjustable the current discharge air cooling setpoint will equal the maxi mum discharge air cooling setpoint Max Spt Point C in Figure 12 exemplifies this When the external signal is between 1 and 5 VDC the current discharge air cooling setpoint will vary linearly between the minimum discharge air cooling setpoint and maximum discharge air cooling setpoint Min Spt and Max Spt Point B in Figure 12 exemplifies this Figure 12 Reset from an External Signal Max Spt 65 F Discharge Cooling Setpoint 1VDC 3VDC 5VDC External Signal Note To use the external signal reset method an exter nal 1 5 VDC or 4 20 mA signal must be connected to the unit controller Airflow Modulation The amount of airflow provided by units in VAV applications is varied by a Dual Motor system Variable Inlet Vanes VIV or Inverters Dual Motor Systems item Name Motor Control Menu 17 Vel Diff 41 FPM Velocity differential required for transfer from high to low speed motor
17. Airflow Waterflow Enabled Output K6 K15 off Closed 0 Flow Closed Off No No O Open Start Up Initialization Closed Minimum Closed Off No No Closed Recirculate Closed Modulating Closed off No No Closed Q Morning Warm Up Modulating Closed off Yes No Open Closed o Heating On Open Modulating Minimum Of ves No Open Closed Fanon On Open Modulating Minimum Of No No Closed Closed FanOnHeaing On Open Modulating Minimum Of ves Economizer On Open Modulating Modulating Modulating No No Closed Closed cosin On Open Modulating Minimum or Open OfforOpen No Yes Closed Closed Unoccupied Econ On Closed Modulating Modulating Unoccupied Cooling On Closed Modulating 6 Closed or Open 9 Unoccupied Heating Closed Yes No Open Closed_ Notes 1 The Fan On output will open 3 minutes after the unit enters the Off state 2 This state is not applicable to cooling only units 3 When the outdoor air enthalpy is low the economizer s outside air dampers will be fully open when the outdoor air enthalpy is high the economizer s outside air dampers will be at minimum position 4 When the outdoor air enthalpy is low the airside economizer s outside dampers will be fully open when the outdoor air enthalpy is high the airside econo mizer s outside dampers will be fully closed 5 Waterside Economizer will be Off if the temperatu
18. be generated for display at the keypad display or PC Table 5 summarizes the alarms that can occur in CAV ZTC units in the order of priority Faults Faults are the highest priority alarms If a fault occurs the unit will be shut down until the alarm condition is gone and the fault is cleared Most fault alarms must be manually cleared Problems Problems have lower priority than faults If a problem occurs the unit will not be shut down but its oper ation will be modified in some way to compensate for the alarm condition Most problem alarms will automatically clear when the alarm conditions that cause them return to normal Warnings Warnings are the lowest priority alarms No control action is taken when a warning occurs it is simply indicated to alert the operator that the alarm condition needs attention Most warning alarms will automatically clear when the alarm conditions that cause them return to normal Alarm priority also exists within each category The alarms in Table 5 are listed according to their priority For example in the fault category the Freeze Shutdown alarm has higher priority than the Fan Failure alarm Table 5 CAV ZTC Unit Alarms Alarm Alarm Type Message Fault Freeze Shutdown Freeze condition occurred while fans were on Manual Smoke Shutdown Smoke detected at discharge air or return air detector O Manual Duct High Limit Duct High Limit in alarm position Manual Zone Sensor Fail Zone temper
19. brief descriptions of the Status cat egory menus Unit Status Menu 1 Unit Status tells you which operating or special state the unit is currently in For more information see the Determining Unit Status section in the Operator s Guide portion of this manual Temperatures Menu 2 Temperatures provides the current temperatures at all connected sensor locations Menu item Cntl Temp displays the current Control Temperature which is the tem perature at the selected representative zone sensor Waterflow Menu 3 Waterflow tells you if waterflow is present and whether the pump is on or off Fan Airflow Status Menu 4 Fan Airflow tells you which fans are currently on and whether there is airflow through the unit Airflow status is sensed by PC7 a differential pressure switch Airflow Modulation Menu 5 Airflow Mod provides the VIV inverter or dual motor control parameters Economizer Menu 6 Economizer tells you the current economizer posi tion and whether it is enabled or disabled Cooling Status Menu 7 Cool Status tells you which kinds of cooling if any are currently allowed H cooling is disabled it tells you why For more information see the Determining Unit Status section in the Operator s Guide portion of this man ual Heating Status Menu 8 Heat Status tells you whether heating is current ly allowed If heating is disabled it tells you why Fo
20. by 16 character LCD display As shown in Figure 3 the current menu is displayed on the top line and the current item is displayed on the bottom line The item line contains one or more fields that convey varying information Figure 3 LCD Display Format Menu Line ltem Line 2 Temperatures Supply Air 65 F Password Protection The MicroTech controller includes password protection to guard against the entry of inadvertent changes When you attempt to change the value of an adjustable parameter with the keypad the controller prompts you to enter the pass word If the correct password is entered the controller will allow you to make changes as desired Fifteen minutes after the last keystroke is made the controller will disallow further changes until the password is re entered The keypad password for all controllers is the following key sequence enter enter enter enter It is not adjustable See Keypad Functions below for more information Keypad Functions The MicroTech controller s keypad consists of 12 pressure sensitive membrane switches which are divided into 4 groups Category Menu Item and Action See Figure 4 Following are descriptions of these groups and the keys they contain Figure 4 Keypad ACTION CLEAR INCR CATEGORY Category Group Acting like bookmarks in the menu structure the keys in the Category group provide quick access to the desired menus By using these ke
21. cussed first Then duct static pressure and building static pressure control are described If either duct or building static pressure control drives the vanes or inverters below a minimum position of 17 during operation the vanes or inverters will be controlled to the maintain the minimum position until the static pressure drops below the setpoint by more than the dead band This mini mum position is required for VIV applications to avoid unsta ble operation due to fan stall conditions This minimum posi tion is required for Inverters to prevent inverter overheating During the Start Initial period a Slower signal is be sent to Inverters so that inverter speed is zero when the fan is start ed In order to avoid unstable operation due to fan stall con ditions Supply Vanes are driven to the fixed minimum posi tion of 17 instead of the closed position during Start Initial period The Inverters and the Supply Vanes are both driven to the 17 minimum position during Post Heat operation after the recirculation period or after heat is provided while VAV boxes remain wide open The purpose of this control is to keep duct pressures from getting too high due to rapidly closing VAV boxes in any Off state other than the Calibrate state a Close sig nal is sent to Variable Inlet Vanes and a Slower signal is be sent to Inverters In the Calibrate state the unit is off The VIV actuator is first driven open for 3 to 4 minutes The actuat
22. enter the Heating state The maximum morning warm up time parameter is pro vided to ensure that the required minimum ventilation air is being supplied after a known time regardless of the space temperature For example if actual occupancy is at 8 00 a m and unit start up is scheduled for 6 30 a m a maximum morning warm up time setting of 90 minutes would ensure that the outside air dampers open to minimum position when building occupancy occurs Discharge Air Low Limit Control Programmable Parameters Keypad Display ID Parameter Men J Wem Name Htg Control Fan On Htg No If heating is enabled menu 8 and there is no zone heating load Fan On state and Fan On Heating Yes the con troller will activate the unit s modulating heating equipment as required to prevent the discharge air temperature from becoming too cool If it falls below the Fan On Heating set point by more than the Discharge Air Heating dead band the operating state will change from Fan On to Fan On Heating If the heating valve is closed and the discharge air tempera ture rises above the cooling SAT setpoint the controller will leave the Fan On Heating state and enter Fan On Except for the discharge air setpoint used Fan On Heating temper ature control is similar to that described above for the heat ing states Fan On Heating is very useful for mixed air applications that require larger amounts of minimum outside air to accommodate for exampl
23. heating is enabled see note below and there is a heating load the controller will activate the unit s modulating heating equipment During occupied periods the operating state will be either Morning Warm up or Heating During unoccupied periods the operating state will be Unoccupied Heating When this occurs the VAV Heat output will open The open VAV Heat output can be used to signal heat cool VAV boxes that the unit is supplying heat When heating is required the controller will modulate the heat output as required to maintain the current discharge air heating setpoint To do this it uses four Step and Wait para meters that are dedicated to discharge air heating tempera ture control 1 discharge air heating dead band 2 dis charge air heating mod limit 3 discharge air heating wait time and 4 discharge air heating max step These step and wait function are modified with a project ahead feature to reduce overshoot of either the SAT heating setpoint or the fan on heating setpoint For most applications the default values for these parameters will provide the best control For more information see the Step and Wait Algorithm and PA Time sections in the MicroTech Control Features por tion of this manual Note You can determine whether heating operation is enabled by displaying the heating status state menu 8 If it is Heating Allowed heating partially is enabled Heating operation is further enabled by
24. heating will be disabled during the Manual Disable state Off Alarm When the unit or its heating equipment is shut down by an alarm all heating will be disabled and the heating status will be Off Alarm Heating Allowed When the outside air is not warm enough to prevent heating operation the heating status will be Heating Allowed In this state the unit will supply heat as required to maintain the heating setpoints Misc Status Heat Output The Heat Output is in the Cool closed position during nor mal operation It is in the Heat open position when 1 heat is supplied 2 during the Recirculation period 3 during the Post Heat period 4 during the Start Initial state to keep the pump off 5 during the unoccupied period when the Fan On output is on to keep the pump off during the unoccupied peri od The Heat Output may not be used for signaling external heaters The Heat Output is displayed on keypad menu 10 Outdr Dmpr The status indicates the position of the outdoor air damper open or closed Head Pressure A water regulating valve WRV modulates the flow to the condenser in response to a refrigerant pressure signal The refrigerant pressure is displayed on keypad menu 10 Humidity and Dewpoint An analog sensor is mounted in either the space or return duct to sense relative humidity The percent relative humidi ty and a calculated dewpoint are both displayed on keypad menu 10 Auto Manual Operation Z WARNING
25. is factory installed and tested in each unit prior to shipment The program loaded into the controller is identified by its software part number also referred to as the Ident This number is printed on the software ID tag a small label affixed to the control panel next to MCB1 For more informa tion refer to the Software ID section of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller The software part number is also encoded in the con troller s memory and is available for display on menu 25 of the keypad display or a PC equipped with MicroTech Monitor software For information on using the keypad display see the Getting Started portion of this man ual Using menu 25 or Monitor software is the most reliable way of determining the controllers software part number Software part number codification is as follows The MicroTech Self contained Air Conditioning Unit Controller is a self contained device that is capable of com plete stand alone operation It can also be included in a net work with other unit and auxiliary controllers Regardless of whether the controller is stand alone or part of a network you can display and modify information in the controller by using any of the following three methods Using the keypad display in the unit s main control panel Getting Started Program number Version numeric Version revision zero then alphabetical The standard softwar
26. overshooting the zone heating setpoint during periods in which the space temperature is changing Using the heating PA time parameter the controller antici pates what the Control Temperature will be if it continues to change at its current rate The controller uses this anticipat ed Control Temperature as the input to its heating control processes The result is that the heating output is increased or decreased early enough to avoid Control Temperature overshoot For most applications the default heating PA time value will provide the best control See the Project Ahead Algorithm section in the MicroTech Control Features por tion of this manual for more information Step and Wait Process Valve Controlled Hot Water When heating is operational Morning Warm up Heating or Unoccupied Heating state the controller modulates the heating valve as required to maintain the current Discharge Air Heating setpoint To do this it uses four Step and Wait parameters that are dedicated to heating temperature con trol 1 Discharge Air Heating dead band 2 Discharge Air Heating mod limit 3 Discharge Air Heating wait time and 4 Discharge Air Heating max step For most applications the default values for these parameters will provide the best control For more information see the Step and Wait Algorithm section in the MicroTech Control Features por tion of this manual If the Step and Wait function fully closes the heati
27. sets the maximum time the actuator can be driven either open or closed during the wait time cycle Depending on the deviation of the controlled variable from setpoint the actual time the actuator is driven is some percentage of the max step This actual driving time is called the step period The greater the deviation is the greater the step period will be After the step period the actuator holds its position for the duration of the wait time This holding time is called the wait period The max step parameter s units are in time seconds or tenths of seconds There is one exception to the above description The actuator will be driven for longer than the max step if the controlled variable is above or below the setpoint by more than the mod limit see below Mod Limit The mod limit sets the gain the responsiveness of the con tro loop to a given variable s deviation from setpoint For a given amount of deviation it determines the actual amount of time the actuator is driven either open or closed during each wait time period If the controlled variable is above or below the setpoint by more than the mod limit the actuator will be driven either open or closed during the entire wait time cycle If the controlled variable is far from setpoint the actuator is effectively driven continuously This feature assures that the controlled variable will approach its setpoint as quickly as possible during transient periods for example
28. the Control Temperature See the Heat Cool Changeover section for more information Note You can either enter a fixed discharge air heating setpoint or allow the controller to reset it automatically See Setpoint Reset below for more information Hot Water or Steam Valve Control Modulating hot water or steam heating is actually a two stage process During stage 1 operation the valve modu lates as required to maintain the discharge air heating set point During stage 0 operation the valve is continuously driven closed but the controller remains in the heating state A stage change can only occur 1 after the heating inter stage timer has expired and 2 if the discharge air temper ature is above or below the discharge air heating setpoint by more than the discharge air heating dead band After any stage change occurs the heating interstage timer starts tim ing There is one additional constraint that applies to the stage down transition from stage 1 to stage 0 The valve must be fully closed before the stage down can occur To determine whether the valve is closed the controller com pares the stroking open time with the stroking closed time Note A stage down transition from stage O would cause the controller to leave the heating state However because the discharge air heating setpoint is typically set well above the mixed air temperature this normally will not occur Usually the controller will leave
29. the Status key For more informa tion see the Determining Unit Status section in the Operator s Guide portion of this manual Operating State Descriptions Off Any of these conditions will prevent the unit from operating All of them must be in the Auto position to allow operation Off service is a safety feature that can only be changed at the unit keypad It can not be set though a remote keypad Off Alarm Off Service Off Manual Off Network Off Unoccupied Off Fan Switch These Off states are prioritized as shown above the Off Alarm state has the highest rank Assigning priority to the Off states is essential For example if a unit is in the Off Service state an operator at a remote network PC would not be able to start that unit by removing the Off Network command The Off Service state occurs when a unit controller is placed into the Shutdown service mode If a unit is in the Off Alarm state nothing could start that unit until the alarm is cleared OO P oh A Start Requested The Start Requested state is a transitional operating state It will be momentarily displayed whenever the unit has been commanded to start Start up Initialization The Start up Initialization operating state always occurs just after the Off and Start Requested states when the unit has been commanded to start During Start up Initialization the unit is prepared for start up For more information on Start up Initializat
30. the discharge air temperature should be closer to the SAT cooling setpoint if the SAT difference is less than twice the SAT error The changeover value to a lower num ber of stages is slightly biased to reduce the number of tran sitions and to bias the supply sir temperature towards the low side The actual equations are Stage up if SAT Cooling Setpoint gt SAT difference 2 Stage down if Cooling Setpoint SAT gt SAT difference 2 1 F ba Discharge Cooling Dead Band Discharge Cooling Setpoint Discharge Cooling Dead Band Stage Dow ETC n z 2 Low EWT Cooling Lockout Programmable Parameters Keypad Display ID Parameter Menu tem Name 13 Clg Control Min OAT 55 F Low Ambient Cooling Lockout Setpoint Low Ambient Cooling Lockout Differential Mechanical cooling will be disabled whenever the EWT falls to the low ambient cooling lockout setpoint When this occurs the cooling status state will usually be Economizer Only if all cooling is not disabled for some other reason The cooling status could also be Temperature Enthalpy Disable indicating that the outdoor air conditions are not suitable for either mechanical or economizer cooling Normally if the setpoints are set properly this situation should never occur When the outdoor air temperature rises above the low ambient cooling lockout setpoint by more than the low ambient cooling lockout differential mechanic
31. the morning warm up or a heating state the actuator for the modulating hot water valve is controlled to maintain the discharge air temperature at the SAT heating setpoint using the step and wait function In the fan on heat ing state the SAT cooling setpoint is maintained instead The step and wait function is modified with a project ahead fea ture to reduce overshoot of either the SAT heating setpoint or the fan on heating setpoint If the discharge air temperature exceeds the SAT heating setpoint by more than its dead band after the heating valve has been in the closed position for the heating stage time the unit leaves the heating or fan on heating state The heating valve is considered to be closed when the heat valve open timer equals zero The heat valve open timer is the net time that the valve is driven open If an open signal is sent to the actuator that time is added to the heat valve open timer Similarly when a close signal is sent to the actuator that time is subtracted from the heat valve open timer Temperature Control Programmable Parameters Keypad Display ID Parameter Menu lem Name 14 Htg Contro Setpoint 100 F Discharge Air Heating Setpoint Stg Timer 5 Min Heating Interstage Timer Dead Band 1 F Discharge Air Heating Dead Band Mod Limit 30 F Discharge Air Heating Mod Limit Time Max Step 60 Sec Discharge Air Heating Max Step PA Time 60 Sec Project Ahead Timer If
32. tion of this manual Service Menu 25 Service contains eight service related items The first item Mode allows you to place the unit into the Shutdown service mode The second item Timers allows you to temporarily speed up most of the controller s process timers For information on these see the Auto Manual Operation section in the Operator s Guide portion of this manual The third through fifth item are setup parameters that specify whether a sensor is connected to the controller The seventh item specifies the baud rate The eighth item IDENT displays the controller s software part number Table 3 Control Menus Default Shown Men Jtem Off Manual 1 Unit Status current unit Auto status Occupied Occ Coo Only Occ Heat Only Occ Fan Only 8 WR Return Calibrate Temperatures Space Netwrk OAT 9 Mixed Cnt Temp Cntl Temp 55 99 F 40 99 2 Temperatures 2 Temperatures 10 F 0 10 F 0 60 Min 60 F Heat Coo Cntl Temp Return Cooling Spt 1 Heating Spt 1 99 F Clg Dead Band 1 0 Htg Dead Band 1 O Htg PA 8 Min 1 i Q Mod Limit 10 F 1 1 O Wait Time 1 Min 1 1 60 Min
33. to operate for another Override Increment For example assume that the Override Increment is two hours One press of the over ride button will provide at least two hours of unit operation If the button is pressed again one hour later the Override Timer will be reset to two hours and thus a total of three uninterrupted hours of operation will result provided the main switch S2 is in the Auto mode and everything else is in the Auto mode also Nontimed Tenant Override A simple SPST switch connected to the External on off ter minals on the output board can be used to override unoccu pied operation When this switch is closed the unit will start and run in the occupied mode provided the main switch 52 is in the Auto mode When this switch is open the unit will be controlled by any active scheduling function internal net work or external time clock If there is no active scheduling function the unit will remain in the unoccupied mode Operator Override Programmable Parameters Keypad Display iD Parameter Name Override Timer 22 Schedule Override 0 00 Hr From the keypad or PC you can manually set the same Override Timer that is automatically set by the tenant over ride switch and Override Increment parameter see Tenant Override above When the Override Timer is set to a non zero value the unit will start and run in the occupied mode regardless of any scheduling features provided the main switch
34. valve in order to maintain the discharge air tem perature at or near the discharge air heating setpoint As its Description of Operation name implies Step and Wait steps or modulates an actu ator either open or closed for a certain amount of time and then waits for the effect on the controlled variable Because Step and Wait uses integral control proportional droop load dependent offset is eliminated The tightest possible control is the result Following is a general descrip tion of Step and Wait operation ACAUTION Grossly misadjusting Step and Wait parameters can cause erratic unit operation and equipment damage Step and Wait parameters should be adjusted only by trained personnel that have a thorough understanding of how they affect overall system operation Regardless of controlled output equipment or controlled variable there are four Step and Wait parameters that reg ulate the control loop action 1 wait time 2 max step 3 mod limit and 4 dead band Following are descriptions of each parameter and an example of how they work together Refer to Figure 18 Wait Time The wait time sets the control loop sampling rate During each wait time cycle the controlled variable s sensor is read and the appropriate output response is generated The wait time parameter s units are in time seconds or tenths of sec onds Max Step The max step which must be less than or equal to the wait time
35. with compressors and no economizer Not available for units with staged zone heating control Units with SAT heating control only Units with modulated heat only Units with duct static pressure control only Units with Airside Economizer Only Units with Waterside Economizer Only Not available on all configurations Alarm Menus Table 4 lists all possible menus and items in the Alarm cate gory The table s range column lists all possible values for each item Following are brief descriptions of the Alarm cat egory menus Current Alarm Menu 26 Curr Alarm tells you what the current alarm is and when it occurred If there is no current alarm the No Active Alarms message will be displayed When the current alarm clears it moves to the Previous Alarm menu For more information see the Alarm Monitoring section in the Operator s Guide portion of this manual Page 14 OM 123 The minimum EWT varies with unit configuration 20 F for units with Head Pressure Control and 55 F for units without Head Pressure Control 21 These control temperature methods are not available in all unit configurations Previous Alarm Menu 27 Prev Alarm tells you what the previous alarm was and when it occurred When the current alarm clears it moves to this menu For more information see the Alarm Monitoring section in the Operator s Guide portion of this manual Compressor Alarm Menu 28 Comp Alarm displays an alarm mes
36. with variable exhaust The variable inlet vanes inverters is controlled based on Building Static pressure instead of Duct Pressure The build ing static pressure sensor input replaces the first duct static pressure sensor input Step and Wait is used to control the variable inlet vanes inverters When the building static pressure gets too low the variable inlet vanes inverters are open speeded up When the building static pressure gets too high the vanes inverters are closed slowed down Regardless of the operating state the controller will modu late the fan airflow as required to maintain the current zone static pressure setpoint whenever the fan is on To do this it uses four Step and Wait parameters that are dedicated to building static pressure control 1 dead band 2 mod limit 3 wait time and 4 max step For most applications the default values for these parameters will provide the best control The result is that proper building pressure is main tained regardless of the building cooling load varying out side air intake or varying exhaust For more information see the Step and Wait Algorithm section in the MicroTech Control Features portion of this manual Optimal Start Programmable Parameter Keypad Display ID 23 Optimal Start Opt Start Off Auto Update Yes Ht Rate 0 400 F M Heat OAT 35 F Ht Factor 25 Min Cl Rate 0 400
37. 50 000 Hrs O Comp 3 0 50 000 Hrs O Comp 4 um 0 50 000 Hrs O Comp 5 TS 0 50 000 Hrs O Comp 6 NE 0 50 000 Hrs E Cooling wees 0 50 000 Hrs 9 Dee ES Overrides pS A cs ee Misc Status Heat Output DA EE 0 255 PSI 0 100 0 100 F 19 Head Pressure 19 Humidity Ctrl 19 Humidity Ctrl Setpointz Humidity Spt DewPt Spt O Head Pres G Humidity TE Notes 1 Not available for units with 100 outdoor air 2 Not available for units with no water flow switch 3 Units with one motor only 4 Units with two motors only 5 Notavailable for one motor units without vanes or inverters 6 Units with duct static pressure sensors only 7 Units with building static pressure control only 8 Units with variable inlet vanes only 9 Units with inverters only 10 Not available for units with no economizer 11 Not available for units with chilled water 12 Not available for units with compressors 13 Not available for units with no heating 14 Units with head pressure control only 15 Units with dehumidification contro only 16 Units with airside economizer only OM 123 Page 9 Control Menus Table 3 lists all possible menus items and adjustable fields in the Control category The table s range col
38. After the start up initialization timer expires the supply fan starts normal temperature control begins and the airflow check timer resets and starts counting down The Fan Failure alarm which indicates loss of airflow is prevented from occurring just after fan start up by the airflow check timer The Fan Failure alarm cannot occur until this timer expires Airflow status is sensed by a differential pressure switch PC7 Heating is required when the space temperature is below the Zone Heating Setpoint by more than the Zone Heating Dead Band If a space sensor is not connected this condi tion is not applicable If heating is not required the unit goes to the Fan On State From the Fan On State the unit can go to Fan On Htg if the SAT drops For more information on these setpo nts see the Heating Multistage or Heating Modulating section as applicable Heat Cool Changeover Temperature Control Programmable Parameters Keypad Display ID Parameter Name Cntl Temp Return Control Temperature Source Cooling Spt 75 F Control Cooling Setpoint Heating spt 68 F Control Heating Setpoint Control Temperature The Control Temperature is the representative zone tem perature When compared with the zone cooling and heating setpoints it determines whether the unit will supply cooling heating or neither It also determines the amount of cooling or heating required to satisfy the load 12 Heat Cool
39. Amp Limit 15 Amp Low Speed motor current limit Output 10 At low airflow requirements the output is de energized and the fan is driven at a low speed by a lower horsepower motor When a large amount of airflow is required the out put is energized and the fan is driven at a high speed by a higher horsepower motor The choice of motor speed is determined by two MicroTech inputs that monitor Low Speed Motor Amps and Air Velocity The unit starts at low speed Switch over to high speed motor occurs when the Low Speed Motor Amps equals the factory set Current Limit This Current Limit is normally the FLA of the low speed motor The Air Velocity when the unit switches from low to high speed is saved by MicroTech The unit switches back to low speed when the Air Velocity drops a fixed velocity below the Air Velocity at switch over from low to high speed To prevent short cycling the unit operates for at least ten minutes at high speed before it changes to low speed Such a minimum operating time is not provided for low speed operation because the low speed motor could trip on overloads if it operates above its FLA ViV inverters Outputs 9 and 10 Variable Inlet Vanes and Inverters are controlled in similar fashion Inverters speed up or slow down the fan and vanes are opened and closed to provide duct static pressure or building static pressure control Control sequences common to both duct and building static pressure control are dis
40. Control for Units with SAT Control 38 Staged Heating Control 38 Modulating Hot Water Control 38 Temperature Control o o ooooooomo o o 38 High Ambient Heating Lockout 39 Setpoint Reset o ooooooooommm m o 39 Morning Warm Up Control 40 Discharge Air Low Limit Control 40 Supply Fan Airflow 0000 41 Static Pressure Control ooo 41 Setpoint Reset cece eee eens 41 Post Heat VIV Ont 41 Unoccupied Contra 41 Heating Night Setback 41 Cooling Night Setup o 42 Head Pressure Contra 42 Building Static Pressure Control 42 Optimal Start 0000 ee eee eee 43 Dehumidification Control 43 Alarm Control 44 Fa a RUE e Ye n 44 Problems Zu iem a RR eric 45 Warnings ura ana Lam eR n CIS Saee 46 MicroTech Control FeatureS sene 47 Step and Wait Algorithm aee aaa 47 About Step and Wait ee 47 Description of Operation 47 Adjusting Step and Wait Parameters 48 McQuay MicroTech and are registered trademarks of McQuay International Monitor and Open Protoco are trademarks of McQuay International 1994 McQuay International Page 2 OM 123 Introduction This manual provides information about the Micro Tech8 con trol system used in the McQuay Self contained Air Conditioning product lin
41. F M Cool OAT 85 F Cl Factor 25 Min When Optimal Start is turned on the number of minutes until startup is calculated before each scheduled start The soft ware uses the start history outdoor air temperature and space temperature to determine when the unit should start lt may start up to four hours before the scheduled start time If the control temperature is below the heating setpoint by more than the dead band Optimal Start will be based on the Heating parameters found in keypad menu 23 If the con trol temperature exceeds the cooling setpoint by more than the dead band Optimal start will be based on the Cooling parameters Startup occurs at the scheduled start time if the Control temperature is in between those limits When heating is required a heating rate that varies with the outside air temperature is calculated based on the fol lowing formula Calculated Heating Rate Ht Rate OAT Heat OAT Heat Factor The minutes to occupancy are calculated by dividing the dif ference between the heating setpoint and the space tem perature by the Calculated Heating Rate Cooling operation is similar The formula is Calculated Cooling Rate CI Rate DAT Cool OAT Cool Factor The minutes to occupancy are calculated by dividing the dif ference between the cooling setpoint and the space temper ature by the Calculated Cooling Rate If the user selects Auto Update the parameters will be revised after each star
42. Initialization Time Airflow 2 Min Airflow Check Time Recirculate Time Reciro 3 Min After the start up initialization timer expires the unit enters the Recirculate operating state During this state the fans operate to allow temperature conditions throughout the unit and space to equalize before temperature control begins Cooling and heating remain disabled the water valve out side air dampers remain closed and the VAV Heat output is opened As soon as Recirculate begins the supply fan starts and the following two timers reset and start counting down 1 the airflow check timer and 2 the recirculate timer The Fan Failure alarm which indicates loss of airflow is prevented from occurring just after fan start up by the airflow check timer Its default value is 2 minutes The Fan Failure alarm cannot occur until this timer expires Airflow status is sensed by a differential pressure switch PC7 After Recirculate if the Control temperature is less than the Zone Heating setpoint minus the Zone Heating dead band the unit enters Morning Warm up The unit will remain in Morning Warm up until one of the following is true 1 Control temperature gt Zone Heating setpoint 2 Unit has been in the occupied state for longer than the maximum Morning Warm Up Timer Fan Start Up 100 Outside Air Units Programmable Parameters Keypad Display ID Parameter Men p 7 Name 20 Timers Airflow 2 Min Airflow Check Time
43. Maximum Morning Warm up Time Mixed Air morning warm up operation occurs just after the recirculation state when the Control Temperature is less than the heating enable setpoint If this is the case the unit con troller will enter the Morning Warm up operating state after Recirculate Morning Warm up is similar to the Heating state the only difference is that the outside air dampers are held shut dur ing Morning Warm up The unit will remain in the Morning Warm Up state until either the Control Temperature equals the heating enable setpoint or the duration of morning warm up operation exceeds the maximum morning warm up time setting default is 90 minutes whichever happens first In either case since the Control Temperature will not have risen above the heating enable setpoint by more than the heating enable dead band when this occurs the controller will enter the Heating state if Heat is enabled Otherwise the unit will enter Fan On The maximum morning warm up time parameter is pro vided to ensure that the required minimum ventilation air is being supplied after a known time regardless of the space temperature For example if actual occupancy is at 8 00 a m and unit start up is scheduled for 6 30 a m a maximum morning warm up time setting of 90 minutes would ensure that the outside air dampers open to minimum position when building occupancy occurs Discharge Air Low Limit Control Programmable Parameters Keypad Displa
44. McQuay Operation Manual Bulletin No OM 123 Air Conditioning September 1994 Part No 579083Y MicroTech Self contained Air Conditioning Unit Controller VAV or CAV DTC Control Used With McQuay Models SWP SWT and SCP Units Table of Contents Introduction sto die ja 3 SoftwarelD elu mia e e ae SEN es 4 Getting Started 000 4 Using the Keypad Display o ooooooo 4 Menu Structure 5 Display Format oooooomoooooomo 5 Password Protecti0n lt 5 Keypad Functions ce eee eee eee 5 Keypad Display Exercises 6 VAV and CAV SAT Menu TableS o 7 Status MenuS leen nnn 7 Control Menus 10 Alarm Menus 14 Operator s Guide cee eee eee eee oo 16 Determining Unit StatUS o ooooomoo o 16 Unit Status ee to GY tee Pes 16 Cooling Status 16 Heating Status 17 Misc Status coo ie MER e ie es 17 Auto Manual Operation 17 Control Mode 17 Service Mode 18 Tenant Override 18 Operator Override 0 19 Fast Timers o ia id 19 Scheduling s Dd pube ar e A 19 Setting Date and Time 19 Daily Scheduling 000 19 Holiday Scheduling ooo 20 Alarm Monitoring 20 About Alarms 20 Displaying Alarms 00 21 Clearing Alarms 22 Setting Alarm Limite 22 Description of Operation ee eee eeee 23 Operating States and Sequence
45. UTION Extreme temperature hazard Can cause damage to system components This MicroTech controller is designed to operate in ambient temperatures from 20 F to 125 F It can be stored in ambi ent temperatures from 40 F to 140 F It is designed to be stored and operated in relative humidity up to 95 non con densing ACAUTION Grossly misadjusting Step and Wait parameters can cause erratic unit operation and equipment damage Step and Wait parameters should be adjusted only by trained personnel that have a thorough understanding of how they affect overall system operation NOTICE This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with this instruction manual may cause interference to radio communications lt has been tested and found to comply with the limits for a Class A digital device pursuant to part 15 of the FCC rules These limits are designed to provide reason able protection against harmful interference when the equipment is operated in a commercial environment Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to cor rect the interference at his own expense McQuay International disclaims any liability resulting from any interfer ence or for the correction thereof OM 123 Page 3 Software ID MicroTech Self contained Air Conditioning Unit controller software
46. age timer has not expired no stag ing action occurs Point 3 The interstage timer expires DTB Area B Area C is greater than DTA Area A and the discharge air temperature is below the setpoint by more than the dead band Therefore cooling is staged down As a result the dis charge air temperature rises the interstage timer is reset and DTA is subtracted from both DTA and DTB This zeros out DTA and leaves DTB equal to Area C Point 4 The interstage timer expires again The dis charge air temperature is above the dead band range but since DTA Area E is not yet equal to DTB Area C Area D no staging action occurs and thus the temperature con tinues to rise Point 5 DTA Area E Area F is equal to DTB Area C Area D Therefore cooling is staged up As a result the discharge air temperature drops the interstage timer is reset and DTB is subtracted from both DTB and DTA This zeros out both DTA and DTB since they are equal Point 6 The interstage timer expires Because the cool ing load is now increasing the discharge air temperature only falls to within the dead band range No staging action occurs for two reasons 1 the discharge air temperature is within the dead band range and 2 DTB Area H is not yet equal to DTA Area G Even if the temperature falls below the dead band range as shown just after Point 6 a stage down does not occur because DTB remains less than DTA The discharge air temperature star
47. aily Scheduling Programmable Parameters Keypad Display ID Menu IL tem Parameter Name 22 Schedule Sunday Schedule Monday Schedule Tuesday Schedule Wednesday Schedule Thursday Schedule Friday Schedule Saturday Schedule Holiday Schedule NMP Sched No N A Network Master Panel Schedule When the unit is in the Auto control mode menu 11 the unit will start and stop according to the controller s internal schedule You can set one start and one stop time for each day of the week and for designated holidays see below An example of how to use the keypad to enter or modify a schedule is given in the Getting Started portion of this man ual As shown in Figure 5 each daily schedule has four adjustable fields start hour start minute stop hour and stop minute The schedule shown in Figure 5 would cause the unit to start up at 6 30 a m and shut down at 6 00 p m every Monday Figure 5 Daily Schedule Fields Start Hour Start Minute Stop Hour ri Stop Minute Mon 06 30 18 00 OM 123 Page 19 For continuous unit operation set the schedule fields to 00 00 23 59 To keep the unit off for the entire day set the schedule fields to 00 00 00 00 this is the default setting Note An internal daily schedule s start time must occur before its stop time otherwise the unit will not start that day If you want to schedule the unit to shut down and then start u
48. al cool ing will be enabled again The default value of this differen tial is 83 F PC adjustable only Setpoint Reset Programmable Parameters ESSE S a WE Menu tem Name 13 Clg Control Setpoint 55 F Supply air Cooling Setpoint Min Spt 55 F Minimum Supply air Cooling Setpoint Min Spt O 90 F Reset Sensor Minimum DN AA Max Spt 70 F Reset Sensor Maximum ae OM 123 Page 31 A variety of reset strategies are available some require field wiring Because they are programmable you can change or eliminate reset strategies as desired When a reset strategy is operational it will automatically change the discharge air cooling setpoint as required You can display the current setpoint but the controller will not let you change it If you do not want reset set the cooling reset type to No Reset default The controller will then allow you to enter a fixed discharge air cooling setpoint The following discharge air cooling reset methods are available Space temperature e Return air temperature Outdoor air temperature Supply fan airflow External 1 5 VDC or 4 20 mA signal Regardless of the reset method the minimum discharge air cooling setpoint and maximum discharge air cooling setpoint define the range of possible discharge air setpoints Reset from a Temperature Sensor The discharge air cooling setpoint can be reset in response to three temperature sensors space retur
49. an On operating state occurs during occupied opera tion when cooling and heating are either not required or dis abled During Fan On the economizer dampers are at mini mum position and cooling and heating are disabled The VAV Heat output is closed auto and normal duct static pressure control is maintained Fan On Heating The Fan On Heating operating state is similar to Fan On The difference is that heating is enabled to prevent the dis charge air temperature from falling below the current dis charge air cooling setpoint during the Fan On Heating state By supplying heat instead of closing the outside air dampers the Fan On Heating state assures that proper dis charge air temperatures are maintained without sacrificing indoor air quality This feature is particularly valuable for buildings in colder climates that have high minimum outdoor air volume requirements For more information see the Heating Modulating sec tion Economizer The Economizer operating state occurs when cooling is required to satisfy the occupied cooling setpoints and free cooling is available During the Economizer state mechani cal cooling and heating are disabled The economizer valve or dampers are modulated to maintain the discharge air cooling setpoint For more information see the Economizer section Cooling When mechanical cooling is required during occupied oper ation the unit enters the Cooling state Depending on the outsid
50. an Open Protocol network the duct static pressure setpoint can be directly set by the building automa tion system In this case the duct pressure reset type para meter must be set to No Reset default Multiple Unit Applications Position Reset Common duct static pressure control for multiple unit appli cations is available with the optional Remote Monitoring and Control RMC Panel To use this control strategy you must select Position as the duct pressure reset type at each unit controller in the group The RMC Panel s controller will then perform the control process using the conditioned duct stat ic pressure values received from each unit controller in the group After each process execution the RMC controller will write the same supply fan inlet vane position to each unit controller Each unit controller will then control its supply vanes to that position Note that the unit controller s duct sta tic pressure setpoint is not used in this strategy However if communications are ever interrupted the affected unit con trollers will use their own duct static pressure setpoints Therefore you should set each unit controller s setpoint so that it matches the others in the group The maximum duct static pressure setpoint is not used For more information see Bulletin No IM 444 MicroTech Self contained Air Conditioning Remote Monitoring and Control Panel Post Heat VIV only Programmable Parameters Menu
51. anging a Setpoint In this exercise assume that the Cooling Control Dead Band is 1 F Using the following procedure you will change this setpoint to 2 F and thus enable mechanical cooling 1 Press control in the Category key group The first menu of the Control category is displayed This is menu 11 Control Mode 2 Press next in the Menu key group twice Menu 13 Clg Control is displayed The first item of this menu Setpoint is also displayed 3 Press next in the Item key group once The Dead Band item is displayed This is the Cooling Control Dead Band Setpoint The default value of 1 F should also be dis played 4 Press either incr or decr in the Action key group The con troller prompts you for the password 5 Press enter in the Action key group four times This is the password The Password Verified message is dis played 6 Press incr until the setpoint is 2 F Notice that the adjustable field flashes during the change 7 Press enter The field stops flashing This means that the new setpoint is locked in Clearing an Alarm In this exercise assume that a fault alarm exists This type of alarm shuts down the unit and keeps it off until the alarm is manually cleared If the conditions that caused the alarm are gone you can clear a fault alarm by using the following procedure 1 Press alarms in the Category key group The first menu of the Alarm category is displayed This is menu 26 Curr
52. ating Sequence Following is an illustration of Step and Wait control For this example the controlled variable is discharge air tempera ture and output device is a hot water valve actuator Output relay K12 drives the valve open when energized and K11 drives the valve closed when energized Refer to Figure 18 Note that Figure 18 is intended to exemplify the different Step and Wait control actions typical operation would be far more steady At the beginning of the first wait time cycle time t1 the discharge air temperature is below the setpoint by more than the dead band Since the deviation from setpoint is approxi mately 60 6 of the mod limit the step period for this cycle ts1 is set equal to 60 of the max step tm During the step period output K12 is energized and thus the hot water valve is driven open As a result the discharge air tempera ture rises At the beginning of the second wait time cycle time t2 the discharge air temperature is within the dead band range and therefore the step period for this cycle ts2 is set equal to zero Since the step period is zero neither K11 nor K12 is energized and thus the hot water valve holds its position The discharge air temperature might continue to rise for example because the heating load has decreased At the beginning of the third wait time cycle time t3 the discharge air temperature is above the setpoint by more than the mod limit Since the deviation from setpoi
53. ation Modulating heating is controlled in a two part process that constitutes a cascade control loop In one part of the process the Change function calculates a Discharge Air Heating setpoint based on the deviation of the Control Temperature from the zone heating setpoint In the other part of the process the Step and Wait function modulates the heating output as required to maintain the discharge air temperature at the current Discharge Air Heating setpoint Note that the controller always sets the Discharge Air Heating setpoint You can display it but the controller will not let you change it Max Step 30 Sec PA Timer 60 Sec Page 36 OM 123 Note You can determine whether heating operation is enabled by displaying the heating status state menu 8 If it is Heating Allowed heating is enabled Change Process Before heating control is activated Start up Initialization Fan On or Recirculate state the controller sets the Discharge Air Heating setpoint equal to the current dis charge air temperature menu 2 if the discharge air temper ature is within the range defined by the minimum and maxi mum Discharge Air Heating setpoints If the discharge air temperature is outside this range the Discharge Air Heating setpoint is set equal to the minimum or maximum Discharge Air Heating setpoint When heating control is activated the Change function starts periodically adjusting the Discharge Air Heating set point in res
54. ature sensor failed while it was the Control Temperature source Manual MAT Sensor Fail Mixed Air Temperature sensor is either shorted or open Manual OAT Sensor Fail OAT temperature sensor is either shorted or open Manual Ret Sensor Fail Return air temperature sensor failed while it was the Control Temperature source Manual Sup Sensor Fail Supply air temperature sensor failed Manual High Return Temp Return air temperature exceeded the High Return Temperature Limit setting menu 15 Manual High Supply Temp Supply air temperature exceeded the High Supply Temperature Limit setting menu 15 Manual Low Supply Temp Supply air temperature fell below the Low Supply Temperature Limit setting menu 15 Manual Fan Fail Airflow not proven after the airflow check timer expired default setting is 2 minutes Manual OA Damper Stuck Outside air damper is stuck Manual Supply Vane Stuck Variable Inlet Vanes are more than 25 open after units been off for three minutes Manual Auto Problem Freeze Problem Freeze condition occurred while fans were off Hi Spd Fan Prob No air flow is sensed after two minutes of operation Manual Lo Spd Fan Prob No air flow is sensed after two minutes of operation Manual Ve Sensor Prob Air velocity is less than 215 FPM Manual Manual Amp sensor equals zero after airfl
55. brate state is a special state that will only occur when the control mode menu 11 is set to Calibrate During the Calibrate state the controller automatically cali Page 16 OM 123 brates the position feedback pots on the economizer damper and supply fan inlet vane actuators lt also calibrates all the unit s static pressure transducers For more information on Calibrate see the following Auto Manual Operation section Cooling Status The cooling status menu 7 tells you whether cooling is enabled or disabled If cooling is disabled the reason is given Following are descriptions of the various cooling sta tus states Off Unoccupied When the unit is shut down by a scheduling function all cool ing will be disabled and the cooling status will be Off Unoccupied Off No Flow When no water is flowing to a unit and no airside economiz eris enabled all cooling will be disabled and the cooling sta tus will be Off No Flow Off Temperature When Economizer is not present or Economizer is disabled and the EWT is too low for compressor operation the cool ing status is Off Temperature Waterside economizer and compressor operation are disabled during Off Temperature Network Disable If the cooling status is Network Disable it means that a net work command has disabled all cooling Switch Disable If the cooling status is Switch Disable it means that the switches on a field supplied device have been set to
56. cable model spe cific installation manual see Table 1 Page 44 OM 123 Outdoor Air Sensor Failure If the outdoor air temperature sensor OAT fails while it is the selected Control Temperature source the OAT Sensor Fail alarm will occur As a result the unit will be shut down It will remain shut down until the OAT Sensor Fail alarm is manually cleared Note that the unit can be quickly restarted by selecting another Control Temperature source before clearing the alarm Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller To determine the location of the RAT sensor refer to the Contro Locations section of applicable model spe cific installation manual see Table 1 Return Air Sensor Failure If the return air temperature sensor RAT fails while it is the selected Contro Temperature source the Ret Sensor Fail alarm will occur As a result the unit will be shut down It will remain shut down until the Ret Sensor Fail alarm is manual ly cleared Note that the unit can be quickly restarted by selecting another Control Temperature source before clear ing the alarm Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller To determine the location of the RAT sensor refer to the Con
57. condition of the zone is used to determine when heating is required The desired space conditions are maintained by external devices such as VAV boxes The unit may be a constant volume unit but it is normally a variable air volume unit Heat also is controlled to raise the discharge air temperature to an acceptable level when the zone does not require heat if the user has selected fan on heating yes Heat is con trolled to maintain the discharge air temperature at the cur rent SAT cooling setpoint Staged Heating Control One or two heating outputs 11 and 12 control one or two electric heat stages The number of stages normally does not change unless the time since the last stage change exceeds the heat stage timer but there are three excep tions e The unit will transition from stage O to stage 1 before the stage timer expires in either heating or fan on heating if the discharge air temperature drops below an acceptable level and the user has selected fan on heating yes The heat stage timer is set to zero before heat is turned on so that the unit moves rapidly through heating stage 0 to heating stage 1 e If heat is disabled or the control temperature rises above the heating zone setpoint by more than the dead band the heating is staged off rapidly without regard to the stage timer The unit remains in the morning warm up state at stage 0 The unit reverts from heating to the fan on state In either the heating or morni
58. curs the cooling interstage timer starts tim ing Page 34 OM 123 There is one additional constraint that applies to the stage down transition from stage 1 to stage 0 The valve must be fully closed before the stage down can occur To determine whether the valve is closed the controller com pares the stroking open time with the stroking closed time Low Ambient Cooling Lockout Programmable Parameters pem Men lem Name 13 Cig Control Min EWT 55 F Low EWT Cooling Lockout Setpoint Mechanical cooling will be disabled whenever the EWT falls to the minimum EWT lockout setpoint The minimum EWT lockout setpoint is 20 F for units with head pressure control and 55 F for units without head pressure control When the minimum EWT lockout occurs the cooling status state will usually be Economizer Only if all cooling is not disabled for some other reason When the EWT temperature rises above the minimum EWT cooling lockout setpoint by more than the EWT lockout differential mechanical cooling will be enabled again The default value of this differential is 3 F Setpoint Reset Programmable Parameters Parameter Keypad Display ID Menu tem Name 13 Clg Control Setpoint 55 F Supply air Cooling Setpoint Min Spt 55 F Minimum Supply air Cooling Setpoint Maximum Supply air Cooling Setpoint Cooling Reset Type Reset Sensor Minimum Cooling Setpoint Reset Sensor Maximum Cooling Se
59. disable cooling All cooling will be disabled during the Switch Disable state Manual Disable If the cooling status is Manual Disable it usually means that the control mode menu 11 has been set to one of the fol lowing Off Manual Occ Heat Only Occ Fan Only or Calibrate The Manual Disable cooling state can also occur if the controller is in the Shutdown service mode menu 25 All cooling will be disabled during the Manual Disable state Off Alarm When the unit is shut down by an alarm all cooling will be disabled and the cooling status will be Off Alarm Compressors Only When the entering water temperature outside air is too warm for free cooling but not cool enough to prevent mechanical cooling operation the cooling status will be Compressors Only in this state the unit will use mechanical cooling as required to maintain the cooling setpoints Economizer operation will be disabled and the water valve outside air damper will be held at its minimum position This status also appears when the unit does not an econo mizer Economizer Only When the entering water temperature outside air is cool enough for free cooling and mechanical cooling is disabled the cooling status will be Economizer Only In this state the unit will use the economizer as required to maintain the cool ing setpoints Mechanical cooling will be disabled All Cooling Allowed When the entering water temperature outside air is cool eno
60. disabled whenever the outdoor air tempera ture is greater than or equal to the high ambient heating lock out setpoint When this occurs the heating status state will be Off OAT Lockout if heating is not disabled for some other reason When the outdoor air temperature drops below the high ambient heating lockout setpoint by more than the high ambient heating lockout differential heating operation will be enabled again The default value of this differential is 3 F PC adjustable only Morning Warm Up Control Programmable Parameters FE Pama i ll Menu tem Name Heat Cool Heating spt 68 F Zone Heating Setpoint Max MWUP 90 Min Maximum Morning Warm Up Time On mixed air units morning warm up operation occurs just after the recirculation state when the Control Temperature is less than the zone heating setpoint minus the zone heating dead band Morning Warm up is similar to the Heating state the only dif ference is that the outside air dampers are held shut during Morning Warm up The unit will remain in the Morning Warm up state until either the Control Temperature equals the zone heating setpoint or the duration of morning warm up operation exceeds the maximum morning warm up time setting default is 90 minutes whichever happens first In either case since the Control Temperature will not have risen above the zone heating setpoint by more than the zone heating dead band when this occurs the controller will
61. e For more infor mation on Calibrate see Control Mode in the Auto Manual Operation section of this manual Airflow Warning If differential pressure switch PC7 detects airflow after the fans are shut down and the airflow check timer expires the Air Flow Warning alarm will occur Unit operation will not be affected by this alarm However if the Air Flow Warning alarm occurs while the Fan On output is energized the con troller will prevent the Fan On output from de energizing until the alarm clears The airflow check timer is set at menu 20 The timer has a default of 2 minutes It starts timing when the fans are shut down The Air Flow Warning alarm will automatically clear when the PC7 contacts open The setting on pressure switch PC7 can be adjusted To determine the location of PC7 refer to the Control Locations section of applicable model specific installation manual see Table 1 Filter Dirty If the pressure switch opens the Filter Dirty alarm will occur Unit operation will not be affected by this alarm The Filter Dirty alarm will automatically clear when the pressure switch closes MicroTech Control Features Step and Wait Algorithm About Step and Wait The MicroTech unit controller uses the Step and Wait algo rithm to control modulating output devices in order to keep a controlled variable at or near the desired setpoint For exam ple Step and Wait would be used to control a modulating hot water
62. e It specifically describes the sequences of operation and programmable options for units with factory equipped variable air volume VAV equipment and units with factory equipped constant air volume dis charge air temperature control CAV STC It also includes information on how to use the keypad display to enter and display data For information on MicroTech components input output service procedures refer to Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller For installa tion and start up instructions and general information on a particular Self contained unit refer to its model specific installation manual see Table 1 Table 1 Model Specific Self contained unit Installation Literature installation amp Maintenance Data Bulletin Number Self contained Model configurations field wiring options and requirements and iM sto AWARNING Electric shock hazard Can cause personal injury or equipment damage This equipment must be properly grounded Connections and service to the MicroTech contro panel must be performed only by personnel that are knowledgeable in the operation of the equipment being controlled AWARNING Excessive moisture in the contro panel can cause hazardous working conditions and improper equipment oper ation When servicing this equipment during rainy weather the electrical components in the main control panel must be pro tected from the rain ACA
63. e indoor air quality requirements If the outdoor air temperature is very cold the mixed air tem perature could become unacceptably cold in these units Because the economizer dampers maintain their minimum position during Fan On Heating minimum ventilation requirements are never violated Fan On Heating is essen tial for 100 outdoor air applications in cold climates Fan On Heating No Yes Fan On Dead Band Dead Band 1 F OM 123 Page 37 Heating Control for Units with SAT Control Programmable Parameters Menu ben Name 14 Htg Control Setpoint 100 F Discharge Air Heating Setpoint Heating Setpoint Heating Setpoint Heating Setpoint Max Spt 20 F Reset Sensor Maximum Heating Setpoint The unit enters the morning warm up or heating states if the control temperature drops below the heating zone setpoint by more than the heating zone dead band and the Discharge Air Temp lt SAT Htg Setpoint SAT Heating Dead Band The unit leaves heating state if the control temperature rises above the heating zone setpoint by more than the heating zone dead band In the morning warm up or heating states heating is con trolled to maintain the discharge air temperature at the SAT heating setpoint This setpoint may be fixed or reset based on the space temperature the return air temperature the outside air temperature or an external signal at analog input 15 The control temperature that indicates the
64. e air enthalpy the economizer valve or dampers will either be fully open or at minimum position during Cooling Cooling will be supplied as required to maintain the dis charge air cooling setpoint On units equipped with modulating chilled water the unit status display will show Cooling during the Cooling state On units equipped with compressors the unit status display will show Cooling Stage during the Cooling state The wildcard character indicates the number of active cooling stages For more information see the Cooling Multistage or Cooling Modulating section as applicable Morning Warm up The Morning Warm up operating state occurs after the recir culation state when heating is required to satisfy the occu pied heating setpoints Morning Warm up is similar to the Heating state the difference is that the economizer and out side air dampers are held shut If heat is not installed or is disabled unit will still enter MWU if control temperature is low The unit will remain in the Morning Warm up state until either the heating load is satisfied or the morning warm up timer menu 20 expires whichever happens first For more information see the Heating One Stage or Heating Modulating section as applicable Heating The Heating operating state occurs when heating is required to satisfy the occupied heating setpoints During the Heating state the outside air dampers are held at their mini
65. e duration parameter For example assume that this year Christmas Eve occurs on a Thursday Your building will be shut down on both Christmas Eve and Christmas Day but will operate normally on the weekend To schedule this holiday set the Holiday Schedule to 00 00 00 00 set the Holiday Date 1 parameter to Dec 24 and set the Holiday Date 1 Duration parameter to 2 Days If any of the 14 holiday dates are not required enter N A and 0 into the fields of those holiday dates except for Holiday Date 1 this is the default setting To use the internal holiday scheduling feature the Network Master Panel Schedule parameter must be set to N A this is the default setting Alarm Monitoring About Alarms The Self contained Air Conditioning Unit controller is pro grammed to monitor the unit for specific alarm conditions that may occur lf the unit controller detects an alarm condi tion it will indicate the alarm identify the alarm and execute appropriate control actions that will fail safe the unit For detailed information on these alarm specific control actions see the Alarm Control section in the Description of Operation portion of this manual Programmable Parameters Parameter Name Alarm indication Alarm indication Keypad Display I Alarm Out Blink Alarm Out Off 25 Service Alarm Indication Under normal non alarm conditions the amber status LED
66. e part number for the program used to control Self contained Air Conditioning unit is 950600020 If the unit s program number does not match this number it is likely that a special program has been loaded into the con troller In this case some of the information in this manual may not be applicable Note The information in this manual should be applica ble with software version revisions following O ie A B etc Using the keypad display in an optional Remote Monitoring and Contro RMC Panel Using an optional PC equipped with Monitor software The following Getting Started sections describe how to use the keypad display For information on using the option al Monitor software package see the user s manual sup plied with the Monitor software Using the Keypad Display The Keypad Display Board shown in Figure 1 is provided with all MicroTech Self contained Air Conditioning Unit Controllers With the keypad display you can monitor oper ating conditions system alarms control parameters and schedules After the password has been entered you can edit setpoints parameters and schedules The optional RMC Panel has a keypad display that can emulate the unit mounted keypad display Once the RMC Panels keypad display is interfaced to the desired unit con troller it operates exactly the same as the unit mounted key pad display Page 4 OM 123 Figure 1 Keypad Display 1 Unit Status Cooling Stage 4
67. el specific installation manual see Table 1 Dry Bulb Temperature Changeover All unit controllers include an internal dry bulb temperature changeover strategy that can be selected if desired When this method is selected the controller compares the outdoor air temperature to the economizer changeover setpoint The external enthalpy control input is then ignored To use the dry bulb method the economizer changeover flag must be set for temperature At the keypad the Enthalpy item s field must be set to No The economiz er changeover setpoint will then be used by the controller to determine whether outdoor air may be used for cooling If the outdoor air temperature is less than or equal to this set point economizer cooling will be enabled If the outdoor air temperature is above this setpoint by more than 1 F econo mizer cooling will be disabled and the outside air dampers will either close unoccupied or go to minimum position occupied Transition Economizer to Mechanical Cooling The transition from economizer state to mechanical cooling state is identical for both waterside and airside economizers A feedback potentiometer on the economizer actuator pro vides the position of the actuator to the MicroTech controller When the economizer position exceeds 90 and the Discharge Air Temperature exceeds the Discharge Air tem perature by more than the dead band the economizer is dri ven open continuously If t
68. emperature Control Programmable Parameters Keypad Display ID Parameter Menu f ltem Name 12 Heat Cool Cooling Spt 75 F Zone Cooling Setpoint Clg Dead Band 1 F Zone Cooling Dead Band Clg PA 12 Min Cooling PA Time Ho PA 8 Min Heating PA Time Mod Limit 10 F Setpoint Mod Limit Wait Time 1 Min Setpoint Wait Time Max Step 10 Setpoint Max Step Supply air cooling Dead Band Economizer Dead Band Economizer Mod Limit Economizer Wait Time Economizer Max Step Economizer PA Timer Dead Band 1 F 13 Clg Control Setpoint __ F Supply air cooling Setpoint Min Spt 55 F Minimum Supply air cooling Setpoint Max Spt 70 F Maximum Supply air cooling Setpoint Dead Band 1 F Mod Limit 60 F Wait Time 30 Sec Max Step 30 Sec PA Timer 60 Sec If the entering water outside air is suitable for free cooling see Changeover Method below the unit controller will attempt to satisfy the cooling load by using economizer before using mechanical cooling If the Control Temperature is greater than the zone cooling setpoint by more than the zone cooling dead band and the discharge air temperature is greater than the SAT cooling setpoint SAT cooling dead band then the control will enter the Economizer or Unoccupied Economizer state Following is description of operation Note You ca
69. emperature falls to night setback setpoint when the unit is in the Off Unoccupied state the unit will start up and run The controller will enter the Unoccupied Heating state after Recirculate OM 123 Page 41 When the zone temperature rises above the night set back setpoint by more than the night setback differential the controller will shut down the fans and return to the Off Unoccupied state The default value of this differential is 3 F After the unit is started heating equipment control during night setback heating operation is similar to that during occu pied operation However since the Control Temperature is likely well below the heating enable setpoint menu 12 heating is enabled and disabled only by the zone tempera ture Emergency Occupied Mode N A for 100 Outdoor Air Units If the zone temperature sensor fails during the Off Unoccupied state when the outdoor air temperature is below 40 F and the night setback setpoint is set above 40 F the unit will start and operate in an emergency occupied mode During this mode the controller will operate just like it does during occupied however the return air sensor will be used as the Control Temperature sensor If the outdoor air tem perature rises above 40 F or if the Zone Sensor Prob alarm clears the emergency occupied mode will end If desired you can disable the emergency occupied mode by setting the night setback setpoint to 40 F Cooling Night Set
70. emperature may drop for a while and then rise again Regardless of the DTA and DTB values another stage up will always occur if the discharge air temperature is above setpoint by more than the dead band after the interstage timer expires After the stage up occurs DTA and DTB are zeroed out The inter stage timer is reset and degree time accumulation resumes Stage Down to Stage Down If the cooling load decreases after a stage down occurs the discharge air tem perature may rise for a while and then drop again Regardless of the DTA and DTB values another stage down will always occur if the discharge air temperature is below setpoint by more than the dead band after the interstage timer expires After the stage down occurs DTA and DTB are zeroed out The interstage timer is reset and degree time accumulation resumes Page 30 OM 123 Typical Operating Sequence Following is an illustration of degree time compressor stag ing control Note that this illustration is meant to show a vari ety of staging possibilities not normal unit operation Refer to Figure 9 which shows nine points on a graph of the dis charge air temperature The cooling interstage timer setting is 5 minutes Point 1 Assume that the controller has just staged up cooling and that DTA and DTB are zero As a result the dis charge air temperature drops and the interstage timer is reset Point 2 DTA Area A equals DTB Area B However since the 5 minute interst
71. en heating or cooling is required For more information see the Unoccupied Control section in the Description of Operation portion of this manual Duct Pressure Menu 17 Duct Pressure contains parameters that are used to maintain duct pressure control These parameters only have meaning if the unit has been equipped for VAV applications j Building Static Pressure Control Menu 17 Bldg Pressure contains parameters that are used to maintain direct building static pressure control These parameters only have meaning if the unit has been equipped with the direct building static pressure control option Motor Control Menu 17 Motor Control contains parameters that are used to maintain dual motor control These parameters only have meaning if the unit has been equipped with dual motors for air flow modulation Page 10 OM 123 Economizer Menu 18 Economizer contains parameters that control the optional economizer For more information see the Description of Operation portion of this manual Head Pressure Contro Menu 19 Head Pressure contains parameters that control the optional head pressure control For more information see the Description of Operation portion of this manual Humidity Contro Menu 19 Humidity Ctrl contains parameter for humidity control For more information see the Description of Operation portion of this manual Timers Menu 20 Timers contains ad
72. er Note that you can wrap around from the first menu to the last menu by pressing the Menu prev key twice Next Key When the Menu next key is pressed the dis play will scroll to the next menu in the structure This action will occur regardless of the current menu number Note that you can wrap around from the last menu to the first menu by pressing the Menu next key twice Item Group After you select a menu you can choose the item you want to display by using the keys in the Item group Refer to Figure 2 Prev Key When the Item prev key is pressed the display will scroll to the previous item in the current menu Note that you can wrap around from the first item to the last item by pressing the Item prev key twice Next Key When the Item next key is pressed the display will scroll to the next item in the current menu Note that you can wrap around from the last item to the first item by pressing the Item next key twice Action Group The Action group keys allow you to clear alarms or change setpoints and parameters in the selected item s field s Note that the password must be entered before any setpoint parameter or schedule changes can be made See Password Protection above for more information Incr Key When the incr key is pressed the entry in the item s selected field will change to the next higher value or next available selection The field being edited will flash until the enter or clear key is pressed
73. er loss of airflow The Recirculate Morning Warm up and Post Heat states are skipped on startup The unit goes from Start Cooling Temperature Control Programmable Parameters Keypad Display ID Parameter Meu lem o Name 13 Clg Control Setpoint 55 F Supply air Cooling Setpoint Method Nearest Average Compressor Staging Method Stg Timer 5 Min Cooling Interstage Timer Dead Band 1 F Supply air Cooling Dead Band If the unit is equipped with an economizer and conditions are suitable for free cooling the unit controller will attempt to sat isfy the cooling load by using economizer before using mechanical cooling See the Economizer section above If the unit is not equipped with an economizer the controller will activate mechanical cooling whenever cooling is required If mechanical cooling is enabled see note below and economizer is either not available or not cool enough to maintain the current discharge air cooling setpoint the con troller will activate mechanical cooling During occupied peri ods the operating state will be Cooling During unoccupied periods the operating state will be Unoccupied Cooling When mechanical cooling is required the controller will stage compressors up or down as required to maintain an average discharge air temperature control or the nearest discharge air temperature control The type of control is selected at menu 13 Clg Control at item Method Nearest Average Following
74. erside Economizer Parameter Name Economizer Changeover Setpoint Keypad Display ID 18 Economizer EWT Diff 3 F The suitability for free cooling is determined by the differen tial between the entering water temperature and the mixed air temperature For free cooling to be enabled the differen tial between EWT and MAT must be equal to or greater than the EWT Diff setting at Menu 18 default is 3 F Changeover Method for Airside Economizer Programmable Parameters Menu tm Name Flag Changeover 75 F Economizer Changeover There are three methods of determining whether the outdoor air is suitable for free cooling Two sense enthalpy dry bulb temperature and humidity and one senses outdoor air dry bulb temperature Enthalpy Changeover The two optional enthalpy changeover methods use external controls One compares the outdoor enthalpy with a set point the other compares the outdoor enthalpy with the return air enthalpy Both enthalpy controls generate a digital changeover signal that the controller receives at one of its inputs To use either of these enthalpy methods the economizer changeover flag must be set for enthalpy At the keypad the Enthalpy item s field must be set to Yes The econ omizer changeover setpoint is ignored by the controller when either enthalpy method is used For more information on the external enthalpy controls refer to the Unit Options portion of the mod
75. expired and 2 if the supply temperature is above or below the discharge air cooling setpoint by more than the discharge air cooling dead band These constraints on compressor staging are essential for preventing short cycling which can reduce compressor life by causing improper oil return and excessive heat buildup in the motor windings After these two condi tions have been met staging occurs as the controller increases or decreases the number of cooling stages when ever such a change results in the discharge air temperature being closer to the SAT cooling setpoint This method will result in fewer stage changes and hence fewer changes in the discharge air temperature and airflow delivered to the zones This method may be more desirable in an application with zones whose cooling loads can be met with discharge air temperatures close to the cooling setpoint Whenever the number of stages is changed a SAT dif ference is calculated This value is the change in the dis charge air temperature between the time that the stage change is initiated and the Cooling Stage Timer expires The assumption is that the supply will change by this amount if the previous stage change is reversed If the SAT Error the difference between the discharge air temperature and SAT cooling setpoint equals half of the SAT difference a stage change should result in a discharge air temperature on the other side of the cooling setpoint with the same SAT error Therefore
76. ey pad simply press the clear key while the current alarm menu 26 is in the display Any alarm may also be cleared by placing the S2 switch on the front of the unit to Off and back to Auto or On The eight previous alarms and the dates and times when they occurred are found in keypad Menu 27 Compressors that are disabled due to alarm conditions are displayed on Menu 28 These alarms do not appear on menu 26 if a higher priority alarm occurred that cleared the compressor alarm and the compressor alarm conditions no longer exist In this situation the compressor alarms may only be cleared through Menu 28 Note Some of the safety devices that detect alarm con ditions require a manual reset at the device before the con troller alarm can clear See Table 5 Page 22 OM 123 Setting Alarm Limits Programmable Parameters Keypad Display ID 15 Alarm Limits Limit Limit Limit Three alarms in Table 5 have adjustable limits that are used to trigger the alarm High Supply Temperature Low Supply Temperature High Return Temperature Although the default settings should be suitable for most applications you can set these alarm limits as necessary with the keypad or a PC The default settings are shown above Description of Operation The following sections describe how the various VAV control them Before changing any setpoints or control parameters processes work to maintain tempera
77. gnal is 1 VDC not adjustable the current discharge air heating setpoint will equal the minimum discharge air heating setpoint Min Spt Point A in Figure 15 exemplifies this When the external signal is 5 VDC not adjustable the current discharge air heating setpoint will equal the maxi mum discharge air heating setpoint Max Spt Point C in Figure 15 exemplifies this When the external signal is between 1 and 5 VDC the current discharge air heating setpoint will vary linearly between the minimum discharge air heating setpoint and maximum discharge air heating setpoint Min Spt and Max Spt Point B in Figure 15 exemplifies this Figure 15 Reset from an External Signal Discharge Heating Setpoint 1VDC 3VDC 5VDC External Signal Note To use the external signal reset method an exter nal 1 5 VDC or 4 20mA signal must be connected to the unit controller For more information see the Field Wiring por tion of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller Page 40 OM 123 Note that in an Open Protocol network the discharge air heating setpoint can be directly set by the building automa tion system In this case the heating reset type parameter must be set to No Reset default Morning Warm Up Control Programmable Parameters Keypad Display ID Parameter Meng tem Name Heat Cool Heating Spt 68 F Heating Enable Setpoint Max MWUP 90 Min
78. he discharge air temperature remains above the discharge air temperature setpoint by more than the dead band after the economizer has been dri ven open for the Cooling Stage Timer the unit transitions to the Mechanical Cooling state Bypass Valve The bypass valve to the condenser is closed in all states except the fan on mechanical cooling and economizer states It is opened in the fan on state when cooling is required so that the program can determine Whether water flow is established AND An accurate entering water temperature The bypass valve is open in the mechanical cooling state when mechanical cooling is required and water is not flow ing through a waterside economizer The bypass valve is opened in the economizer state if an airside economizer is installed and mechanical cooling is anticipated or the posi tion of a waterside economizer does not exceed 90 The bypass valve is not controlled on chilled water units The bypass valve may be linked electrically slaved to the economizer valve so that the bypass valve closes as the economizer opens This provides nearly constant flow of water through the unit regardless of the requirements of the economizer The bypass output relay is not wired to the valve in this situation 100 Outside Air Units When the outside air damper output is on the outside air dampers open during Start Initial and all operating states The outside air damper remains open for 30 seconds aft
79. heating setpoint Min Spt Point C in Figure 14 exemplifies this When the temperature at the selected reset sensor is less than or equal to the reset sensor maximum heating setpoint Max Spt O the current discharge air heating setpoint will equal the maximum discharge air heating setpoint Max Spt Point A in Figure 14 exemplifies this OM 123 Page 39 When the temperature at the selected reset sensor is between the reset sensor minimum and maximum heating setpoints Min Spt and Max Spt the current dis charge air heating setpoint will vary linearly between the minimum and maximum discharge air heating setpoints Min Spt and Max Spt Point B in Figure 14 exempli fies this Figure 14 Reset from a Temperature Sensor Max Spt A Min Spt 80 F Discharge Heating Setpoint 1 66 F 68 F 70 F 72 F 74 F Max Spt Min Spt O Ambient Temperature Note To use the space temperature or outdoor air reset method a zone temperature sensor or OAT sensor must be field installed and connected to the unit controller Reset from an External Signal The discharge air heating setpoint can be reset in response to an external signal When this method is used an external 1 5 VDC or 4 20mA signal controls the current discharge air heating setpoint The reset sensor minimum and maxi mum heating setpoints are not used This reset action is illustrated in Figure 15 When the external si
80. idification the heaters are controlled normally to maintain acceptable Discharge Air and Space Temperature conditions The Fan On Hts feature is enabled automatically so that the heaters will be controlled to main tain the Fan On Heating setpoint if the Discharge Air gets too cold When Dehumidification is initiated during any state other then Mechanical Cooling the number of compressors is con trolled to minimum stages then increased to the maximum number of stages if the relative humidity or dewpoint stays above the setpoint by more than the dead band for more than the Cooling Timer The number of compressors decreases to the minimum number of stages if the relative humidity or dewpoint drops below the setpoint by more than the dead band Dehumidification terminates if the relative humidity or dewpoint drops below the setpoint by more than the dead band and the unit has been operating at the mini mum number of stages for more than the Cooling Timer When Dehumidification is initiated during Mechanical Cooling operation is similar to that described above except that the number of stages of cooling is set to the maximum number of stages if the number of cooling stages prior to dehumidification equal or exceeds the minimum number of dehumidification stages When Dehumidification terminates the number of cooling stages is set to whatever it was when the unit entered dehumidification OM 123 Page 43 Alarm Control Following are desc
81. ilable some require field wiring Because they are programmable you can change or eliminate reset strategies as desired When a reset strategy is operational it will automatically change the discharge air heating setpoint as required You can display the current setpoint but the controller will not let you change it If you do not want reset set the heating reset type to No Reset default The controller will then allow you to enter a fixed discharge air heating setpoint The following discharge air heating reset methods are available Space temperature Return air temperature Outdoor air temperature External 1 5 VDC or 4 20 mA signal Regardless of the reset method the minimum discharge air heating setpoint and maximum discharge air heating set point define the range of possible discharge air setpoints Reset from a Temperature Sensor The discharge air heating setpoint can be reset in response to three temperature sensors space return air or outdoor air When any of these methods is used the current dis charge air heating setpoint is determined by the current tem perature at the selected reset sensor This reset action is illustrated in Figure 14 The space temperature reset method is shown When the temperature at the selected reset sensor is greater than or equal to the reset sensor minimum heating setpoint Min Spt the current discharge air heating set point will equal the minimum discharge air
82. ill prevent the setpoints and Dead Bands from being set so that there is overlap of the dead band ranges In doing this the controller will always give the zone cooling setpoint the highest priority Regardless of whether you lower the cooling setpoint raise the heating setpoint or increase either dead band the con troller will automatically lower the heating setpoint enough to prevent the dead band ranges from overlapping Note The above description assumes that cooling and heating control is enabled If cooling or heating control is dis abled the cooling or heating equipment cannot be activated by the Control Temperature Either could be disabled for a variety of reasons For example the outdoor air could be too cold for mechanical cooling or too warm for economizer cooling You can find out by displaying the cooling status state menu 7 or heating status state menu 8 Note During the Fan On Heating operating state the heating equipment can operate to maintain an acceptable discharge air temperature even though heating control is not required by the Control Temperature For more information see the Heating Multistage or Heating Modulating sec tion as applicable Typical Operating Sequence Following is an illustration of heat cool changeover control Refer to Figure 8 When the Control Temperature rises to the cooling enable setpoint plus the cooling dead band Point A all cooling economizer and mechanical
83. in chronological order The first item in the alarm buffer is more recent than the next item and so on When a new alarm is added to the alarm buffer the last item in the buffer is dropped Keypad Display ID Parameter Name 26 Curr Alarm Alarm Message 27 Prev Alarm Clear Buffer No Clear Buffer Flag Current Alarm E T If desired you can clear the alarm buffer by changing the When the controller indicates that an alarm condition has Clear Buffer Flag to Yes It will a om tically gege lad occurred you can find out what it is and when it happened to No after the buffer is cleared by displaying the current alarm menu 26 at the keypad or PC To do this at the keypad simply press the alarms key The current alarm will remain current until either it clears see below or a higher priority alarm occurs OM 123 Page 21 Clearing Alarms Before any alarm can be cleared the alarm conditions that caused it must have returned to normal When the alarm conditions are gone an alarm may be cleared either auto matically or manually See Table 5 Clearing an alarm is the same as resetting an alarm Alarms are arranged in increasing priority A higher prior ity alarm replaces a lower priority alarm An auto reset alarm will immediately clear whenever the alarm conditions that caused it disappear You can clear a manual reset alarm at the keypad display or PC To clear an alarm from the k
84. ing wait time and 4 discharge air cooling max step The Step and Wait function is modified with a Project Ahead feature to reduce overshoot For most applications the default values for these parameters will provide the best control For more information see the Step and Wait Algorithm section in the MicroTech Control Features por tion of this manual 13 Clg Control Note You can determine whether mechanical cooling operation is enabled by displaying the cooling status state menu 7 If it is All Cooling Allowed mechanical cooling is partially enabled Cooling operation is further enabled by the Control Temperature See the Heat Cool Changeover sec tion for more information Note You can either enter a fixed discharge air cooling setpoint or allow the controller to reset it automatically See Setpoint Reset below for more information Chilled Water Valve Control Modulating chilled water cooling is actually a two stage process During stage 1 operation the valve modulates as required to maintain the discharge air cooling setpoint During stage 0 operation the valve is continuously driven closed but the controller remains in the cooling state A stage change can only occur 1 after the cooling inter stage timer has expired and 2 if the discharge air temper ature is above or below the discharge air cooling setpoint by more than the discharge air cooling dead band After any stage change oc
85. installed and con nected to the unit controller For more information see the Field Wiring portion of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller Reset from Supply Fan Airflow The discharge air cooling setpoint can be reset in response to the supply fan airflow When this method is used the cur Page 32 OM 123 rent discharge air cooling setpoint is determined by the cur rent supply fan inlet vane position or inverter speed The reset sensor minimum and maximum cooling setpoints are not used This reset action is illustrated in Figure 11 When supply fan airflow is selected as the type of reset the cooling setpoint decreases from the maximum value to the minimum value as the fan speed or vane position increases The Cooling Discharge Air Temperature Setpoint is controlled as indicated graphically below When the supply fan inlet vane position is between 30 and 90 open the current discharge air cooling setpoint will vary linearly between the minimum and maximum discharge air cooling setpoints Min Spt and Max Sptz Point B in Figure 11 exemplifies this Figure 11 Reset from Supply Fan Airflow Discharge Cooling Setpoint I 60 70 80 90 10096 Max Spt Min Spt O Supply Fan Airflow Reset from an External Signal The discharge air cooling setpoint can be reset in response to an external signal to input 15 When this method is used an external 1 5 VDC or
86. ion see the Start up Control section Recirculate The Recirculate operating state begins after Start up Initialization when the fan is energized It allows temperature conditions throughout the unit and space to equalize before temperature control begins This feature is particularly important for applications in which the return air temperature sensor is being used for heat cool changeover control For more information on Recirculate see the Start up Control section Post Heat Post Heat eliminates duct overpressurization problems that could otherwise occur during the transition from heating to cooling operation when the VAV boxes regain zone temper ature control Post Heat always occurs after the Recirculate Heating or Unoccupied Heating states Typically the VAV boxes are forced to a wide open position during operation in these states to facilitate rapid heat transfer to the space As a result since they are still controlling duct static pressure the supply fan inlet vanes open wide and deliver maximum air flow During Post Heat normal duct static pressure control is Page 24 OM 123 overridden and the supply fan inlet vanes are forced to a minimum position 17 open fixed The economizer main tains its previous position closed or minimum cooling and heating are disabled and the VAV Heat output remains open For more information on Post Heat see the Supply Fan Airflow section Fan On The F
87. is a description of Average and Nearest discharge air temperature control initial to Heating if Heating is enabled and the Space Temperature is less than the Zone Heating Setpoint by more than its dead band If not the unit goes to Fan On The unit is then controlled in the normal manner Multistage Note You can determine whether mechanical cooling operation is enabled by displaying the cooling status state menu 7 If itis either All Cooling Allowed or Compressors Only mechanical cooling is partially enabled Cooling oper ation is further enabled by the Control Temperature See the Heat Cool Changeover section for more information Note You can either enter a fixed discharge air cooling setpoint or allow the controller to reset it automatically See Setpoint Reset below for more information Average Degree Time Compressor Staging This method is useful if the SAT must be provided at the desired setpoint to meet the cooling load of one or more spaces Except during unit shutdown a stage change can only occur 1 after the cooling interstage timer has expired and 2 if the supply temperature is above or below the discharge air cooling setpoint by more than the discharge air cooling dead band These constraints on compressor staging are essential for preventing short cycling which can reduce compressor life by causing improper oil return and excessive heat buildup in the motor windings After these two c
88. is to select the Normal service mode at the keypad on the unit This feature is meant to be used by a service technician who needs both power in the unit and assurance that the unit will not start unexpectedly Tenant Override Programmable Parameters Keypad Display ID Parameter Name Ovrde Inc 2 00 Hr Override Increment There are two types of tenant override functions timed and nontimed Both types place the unit into occupied operation regardless of any scheduling features The control mode menu 11 must be set to Auto to use the tenant override features Additional information is provided in the Field Wiring portion of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller Timed Tenant Override The tenant override switch provided with several of the zone temperature sensor packages can be used to override unoc cupied operation for a preprogrammed time period You can set this time period with the Override Increment parameter which can be set for any amount of time up to 5 hours in 15 minute increments default is 2 hours at Menu 20 When an occupant presses the push button switch on the zone sensor SPT1 the Override Timer menu 22 is set equal to the Override Increment The unit will then start and run until the Override Timer expires If the tenant override switch is pressed again while the unit is operational the Override Timer will reset and the unit will continue
89. justable timer settings that control the duration of initialization start up airflow check tenant override post start up recirculation and morning warm up operation The tenant override timer setting is described in the Auto Manual Operation section in the Operator s Guide portion of this manual The recirculate morning warm up and low supply temperature alarm delay timer settings are described in the Description of Operation portion of this manual Set Time Date Menu 21 Set Date Time allows you to adjust the current day date and time For more information see the Scheduling section in the Operator s Guide portion of this manual Schedule Menu 22 Schedule contains the internal scheduling para meters It also includes an operator override timer that can be used to start and run the unit for a specified time period For more information see the Scheduling and Auto Manual Operation sections in the Operator s Guide portion of this manual Optimal Start Menu 23 Optimal Start contains the parameters for Optimal Start For more information see the Description of Operation portion of this manual Holiday Date Menu 24 Holiday Date allows you to schedule 14 holiday dates Each date can be assigned a duration from 1 to 5 days On each day of the holiday period the holiday sched ule entered under menu 22 is used For more information see the Scheduling section in the Operator s Guide por
90. lyz 1 90 250 F Temperatures Supply Air Lo Supply 40 F 1 20 50 F Temperatures Supply Air O HiReturn 120 F 1 90 150 F Temperatures Return Air OM 123 Page 11 Table 3 Control Menus Cont d Menu 16 Unocc Htg Clg Cooling Spt Name Default Shown o mw Switch Key Destination ue Menu 55 99 F 2 Temperatures 85 F Heating Spt 55 F 40 99 F 2 Temperatures Cig Diff 0 10 F 3 F Htg Diff 3F 0 10 F 17 Duct Pressure Duct Spt 1 00 WC 0 5 00 WC 3 Airflow Mod Deadbd 0 08 WC 0 000 1 00 WC Max Spt 2 00 WC 20 4 00 WC Reset No Heset Position No Reset Mod Lim 0 020 0 250 WC 0 040 WC Wait Time 20 Ten 10 Ten 60 Sec Max Step 17 Bldg Pressure Zone Spt SEU 10 Ten 60 Sec 0 250 0 250 WC 20 Ten 0 050 WC Min Pos 60 0 100 Min Speed 60 0 100 Deadbd 0 008 WC 0 000 0 100 WC Mod Lim 0 040 WC 0 020 0 250 WC Wait Time 20 Ten 10 Ten 60 Sec Min Airflow Max Step 20 Ten 10 Ten 60 Sec 17 9 Motor Control Vel Diff 41 FPM 0 410 FPM Amp Limit 15 Amps 0 99 Amps 5 AirFlow Mod Current 6 Economizer Position 10 0 100
91. me 14 Htg Control Min Spt 60 F Minimum Supply air heating Setpoint Max Spt 120 F Maximum Supply air heating Setpoint Heating Interstage Time If heating is enabled see note below and there is a zone heating load the controller will activate the first stage of electric heat as it enters the Morning Warm up Heating or Unoccupied Heating state This will occur when the Control Temperature is below the zone heating setpoint by more than the zone heating dead band value Following is a description of operation Note You can determine whether heating operation is enabled by displaying the heating status state menu 8 If it is Heating Allowed heating is enabled Electric Heat Staging After the heating interstage timer expires staging occurs as the controller attempts to 1 keep the Control Temperature close to the zone heating setpoint and 2 keep the dis charge air temperature within the range defined by the min imum and maximum Discharge Air Heating setpoints After any stage up or stage down action the heating interstage timer resets and starts counting down again Except during unit shutdown a stage change can only occur after the heating interstage timer has expired This constraint on electric heat staging is essential for preventing short cycling which can reduce contactor life It also pro vides better temperature control Stage Up Action A stage up can occur for two reasons 1 the Control Temperat
92. mum position The VAV Heat output is open and normal duct sta tic pressure control is maintained For more information see the Heating One Stage or Heating Modulating section as applicable Unoccupied Economizer If the outside air is suitable for free cooling when night setup operation is required the unit will start and operate in the Unoccupied Economizer state During Unoccupied Economizer the outside air dampers are modulated to main tain the discharge air cooling setpoint and the occupied out put is closed The VAV Heat output is closed auto and nor mal duct static pressure control is maintained For more information see the Unoccupied Control sec tion Unoccupied Cooling When mechanical cooling is required during unoccupied operation the unit enters the Unoccupied Cooling state Depending on the outside air enthalpy the economizer valve or dampers will either be fully open or closed during Unoccupied Cooling Cooling will be supplied as required to maintain the discharge air cooling setpoint On units equipped with modulating chilled water the unit status display will show Unoccupied Cooling during the Unoccupied Cooling state On units equipped with compres sors the unit status display will show Unoccupied Cooling Stage during the Unoccupied Cooling state The wildcard character indicates the number of active cooling stages For more information see the Unoccupied Control sec tion
93. n Dec 0 31 1 5 Days N A Jan Dec 0 31 1 5 Days N A Jan Dec 0 31 1 5 Days N A Jan Dec 0 31 1 5 Days N A Jan Dec 0 31 1 5 Days N A Jan Dec 0 31 1 5 Days N A Jan Dec 0 31 1 5 Days f H ck Jk Jk ck zk Je bk bie bie H OM 123 Page 13 Table 3 Control Menus sce eae Name Default Shown ange Mode Normal Po Switch Key Destination os Destination Normal Shutdown Timers Normal Normal Fast Space Sensor No Yes Return Sensor No Yes OAT Sensor No Yes Alarm Out oft Blink Port A Baud 1200 2400 9600 IDENT 950600020 Notes 1 Not available for 100 Outside Air Control Units 2 Units with Two Motors Only 3 Units with building static pressure only 4 Not available for units with no economizer 5 Not available for units with chilled water 6 Not available for units with compressors 7 Not available for units with no heating 8 Units with head pressure control only 9 Units with dehumidification control only Units with zone heating control only 11 Units with zone control of modulated heating or cooling Not available for zone control units
94. n air or outdoor air When any of these methods is used the current dis charge air cooling setpoint is determined by the current tem perature at the selected reset sensor This reset action is illustrated in Figure 10 The outdoor air reset method is shown When the temperature at the selected reset sensor is greater than or equal to the reset sensor minimum cooling setpoint Min Spt the current discharge air cooling set point will equal the minimum discharge air cooling setpoint Min Spt Point C in Figure 10 exemplifies this When the temperature at the selected reset sensor is less than or equal to the reset sensor maximum cooling setpoint Max Spt Q the current discharge air cooling setpoint will equal the maximum discharge air cooling setpoint Max Spt z Point A in Figure 10 exemplifies this When the temperature at the selected reset sensor is between the reset sensor minimum and maximum cooling setpoints Min Spt and Max Spt the current dis charge air cooling setpoint will vary linearly between the min imum and maximum discharge air cooling setpoints Min Spt and Max Spt Point B in Figure 10 exemplifies this Figure 10 Reset from a Temperature Sensor Max Spt A Min Spt 55 F Discharge Cooling Setpoint I 1 4 60 F 70 F 80 F 90 F 100 F Max Spt Min Spt O Ambient Temperature Note To use the space temperature reset method a zone temperature sensor must be field
95. n determine whether economizer operation is enabled by displaying the cooling status state menu 7 If it is either All Cooling Allowed or Economizer Only econ omizer cooling operation is enabled Step and Wait Process When the economizer is operational Economizer or Unoccupied Economizer state the controller modulates the waterside economizer valve airside economizer dampers as required to maintain the current discharge air cooling set point To do this it uses four Step and Wait parameters that are dedicated to economizer temperature control 1 econ omizer dead band 2 economizer mod limit 3 economiz er wait time and 4 economizer max step For most appli cations the default values for these parameters will provide the best control For more information see the Step and Wait Algorithm section in the MicroTech Control Features portion of this manual OM 123 Page 27 If Step and Wait adjusts the economizer s outside air dampers to the minimum position during occupied periods the controller will leave the Economizer state and enter Fan On This can only happen if the Control Temperature is less than the SAT cooling setpoint by more than the SAT cooling dead band PA Time Use of the Project Ahead Time or PA Time improves control by reducing overshoot when the measured variable must be changed to maintain the desired setpoint The PA Time does this by modifying the action of the Step and Wait functio
96. n so that control is based on what the value of the measured vari able will be after the PA time has passed instead of what it is now Use of such a Project Ahead Time for control stops the valve from opening or closing when it is rapidly approaching the setpoint It also allows the position of the valve to start responding in the opposite direction before the measured variable passes through the dead band This combination of normal Step and Wait parameters and a Project Ahead Time provides Proportional Integral or PI control Mechanical Cooling If the entering water temperature outdoor air enthalpy changes from low to high at any time while the economizer is operational Economizer or Unoccupied Economizer state the transition from economizer operation to mechani cal cooling operation will occur During occupied operation the outside air dampers will go to the current minimum posi tion setting see Minimum Ventilation Air Volume Control below During unoccupied operation the outside air dampers will close The transition from economizer operation to mechanical cooling operation will also occur when conditions are such that the entering water temperature outside air is cool low enthalpy but unable to satisfy the cooling load Normally this will happen when 1 the waterside economizer valve airside economizer damper is more than 90 open and 2 the discharge air temperature is above the discharge air cooling setpoint by more
97. n time regardless of the space temperature For example if actual occupancy is at 8 00 a m and unit start up is scheduled for 6 30 a m a maximum morning warm up time setting of 90 minutes would ensure that the outside air dampers open to minimum position when building occupancy occurs Discharge Air Low Limit Control Programmable Parameters Parameter Name Keypad Display ID Htg Control Fan On Htg 60 Fan On Heating Setpoint Menu tem Fan On Htg No Fan On Heating No Yes Dead Band 1 F Fan On Dead Band If heating is enabled menu 8 and there is no zone heating load Fan On state and Fan On Htg Yes the controller will activate the unit s electric heating equipment as required to prevent the discharge air temperature from becoming too cool If it falls below the cooling SAT setpoint by more than the Discharge Air Heating dead band the operating state will change from Fan On to Fan On Heating If the discharge air temperature rises above the cooling SAT setpoint by more than the Discharge Air Heating dead band when at stage 0 the controller will leave the Fan On Heating state and enter Fan On Stage timers also apply except for stage 0 to stage 1 Fan On Heating temperature control is similar to that described above for the heating states The difference is that the staging action is controlled by the discharge air temper ature parameters instead of the zone temperature parame ters Fan On Heating is
98. ng minimum ventilation requirements are never violated Supply Fan Airflow Static Pressure Control Programmable Parameters Menu Mem Name 17 Duct Pressure Duct Static Pressure Setpoint Max Step 20 Ten Except during the Post Heat state see below the controller will modulate the supply fan airflow as required to maintain the current duct static pressure setpoint whenever the fans are on To do this it uses four Step and Wait parameters that are dedicated to duct static pressure control duct pressure dead band duct pressure mod limit duct pressure wait time and duct pressure max step For most applications the default values for these parameters will provide the best control For more information see the Step and Wait Algorithm section in the MicroTech Control Features por tion of this manual Parameter Applications with Two Pressure Sensors On units that use cooling only a second duct static pressure sensor is optional If a second sensor is connected the con troller will automatically select the lower of the two sensed pressures and use this value to control the supply fan air flow On larger buildings this strategy can be used to assure that adequate static pressure is available throughout the VAV system Setpoint Reset Programmable Parameters Keypad Display ID Parameter Menu Wem Name 18 Duct Pressure Maximum Duct Static Pressure Setpoint Note that in
99. ng valve during occupied periods the controller will leave the Heating state and enter Fan On This can only happen if the Control Temperature is greater than the zone heating set point by more than the zone heating dead band To deter mine whether the valve is closed the controller compares the stroking open time with the stroking closed time Note The heating interstage timer is ignored when mod ulating hot water heat is used PA Time Use of the Project Ahead Time or PA Time improves control by reducing overshoot when the measured variable must be changed to maintain the desired setpoint The PA Time does this by modifying the action of the Step and Wait function so that control is based on what the value of the measured vari able will be after the PA time has passed instead of what it is now Use of such a Project Ahead Time for control stops the valve from opening or closing when it is rapidly approaching the setpoint lt also allows the position of the valve to start responding in the opposite direction before the measured variable passes through the dead band This combination of normal Step and Wait parameters and a Project Ahead Time provides Proportional Integral or PI control High Ambient Heating Lockout Programmable Parameters Keypad Display ID Parameter L Men tem Name Htg Control Max OAT 55 F High Ambient Heating Lockout Setpoint High Ambient Heating Lockout Differential Heating will be
100. ng warm up state the number of heating stages decreases when the stage timer has expired and the discharge air temperature exceeds the SAT heating setpoint by more than the SAT heating dead band If the unit is in heating stage zero and the discharge air tem perature exceeds the applicable setpoint by more than its Page 38 OM 123 dead band after the stage time the unit leaves the heating or fan on heating state In either the heating or morning warm up state the number of heating stages increases when the stage timer has expired and the discharge air temperature is below the SAT heating setpoint by more than the SAT heating dead band In the fan on heating state the stages of electric heat are controlled to maintain the current SAT cooling setpoint as described below The number of electric heat stages increases if both of the following are true The time since the last stage change exceeds the stage timer or the number of heating stages equals zero The discharge air temperature is below the SAT cool ing set point by more than the SAT heating dead band The number of electric heat stages decreases when both of the following are true The time since the last stage change exceeds the stage timer The discharge air temperature exceeds the applicable minimum setpoint by more than the SAT heating dead band Modulating Hot Water Control The two heating outputs 11 and 12 close and open a mod ulating valve In
101. ns Airflow Mixed Air FR 0 255 F e Space F 0 255 F O Return Air F 0 255 F Outdr Air F 100 155 F O Waterflow Cooling Spt Hi Return 16 Unocc Htg Clg 15 Alarm Limits 14 Htg Control RALA Pump Airflow Supply Fan e Supply Fan Fan Op G Airflow Mod O Velocity 0 1675 FPM O Current Amps 0 30 Amps 17 Motor Control Amp Limit O Duct P WC 0 4 00 WC 17 Duct Pressure Duct Spt O Bldg P WC 0 25 0 25 WC 17 Bldg Pressure Zone Spt Vane Pos K 0 100 e 0 100 0 100 Disabled Enabled Fan Speed Position Econo Min Airflow Enthalpy 18 Economizer E 18 Economizer nm Page 8 OM 123 Table 2 Status Menus cont d um ame LI ns AA ange Men em Cool Status Off Unoccupied Off No Flow Off Temperature Network Disable Switch Disable Manual Disable Off Alarm No Cooling Avail Compressors Only Economizer Only All Clg Allowed Heat Status Off OAT Lockout Off Unoccupied Network Disable Switch Disable Manual Disable Off Alarm Heating Allowed Operating Hrs Fan 0 50 000 Hrs S Hi Spd Fan 0 50 000 Hrs O Lo Spd Fan EE 0 50 000 Hrs O Comp 1 0 50 000 Hrs O Comp 2 EM 0
102. nt is greater than the mod limit the step period for this cycle ts3 is set equal to wait time During the step period output K11 is energized and thus the hot water valve is driven closed for the full duration of the wait time cycle As a result the dis charge air temperature drops rapidly McOuay International 13600 Industrial Park Blvd P O Box 1551 Minneapolis MN 55440 t Wait Time Adjusting Step and Wait Parameters Appropriate default Step and Wait parameter values are loaded into each controller at the factory see Table 3 These default values will provide proper control for most applications therefore field tuning is usually not required If the default values do not provide acceptable system opera tion they can be adjusted If the controlled variable hunts above and below its set point or if it overshoots the setpoint too much during start up or other abrupt changes in unit operation Step and Wait control should be slowed down by decreasing the max step value increasing the mod limit value or both Step and Wait control can also be slowed down by increasing the wait time In some cases increasing the dead band can also eliminate hunting problems If the controlled variable does not approach its setpoint fast enough during start up or other abrupt changes in unit operation Step and Wait control should be speeded up by increasing the max step value decreasing the mod limit value or both S
103. o Sat by using the next key but it would have taken longer 4 Press enter in the Action key group The second field start minute flashes indicating that it can be edited Since the desired schedule is 00 30 17 00 the first field start hour does not need to be changed By pressing enter instead of incr you can bypass this field 5 Press incr until the start minute field is 30 Notice that the adjustable field flashes during the change 6 Press enter The second field stops flashing and the third field stop hour starts flashing This means that the new start minute is locked in and the stop hour can be edited 7 Press incr until the stop hour field is 17 8 Press enter The third field stops flashing and the fourth field stop minute starts flashing 9 Since the stop minute field does not require editing press enter again The fourth field stops flashing thus complet ing the edit Note that the same result could have been accomplished by pressing the clear key instead of the enter key VAV and CAV DTC Menu Tables The following tables show every menu item and field in the menu structure These menus and items can all be dis played with the keypad display Monitor software provides many additional monitoring features and adjustable parame ters Status Menus Table 2 lists all possible menus and items in the Status cat egory The table s range column lists all possible values for each item Following are
104. on a stage up will occur Note The controller will not allow you to set the minimum Discharge Air Heating setpoint above the zone heating set point This restriction will ensure better zone temperature control during heating operation Project Ahead The Project Ahead algorithm works to prevent the Control Temperature from overshooting the zone heating setpoint during periods in which the space temperature is changing while it is far from setpoint for example just after start up Using the heating PA time parameter the controller antici pates what the Control Temperature will be if it continues to change at its current rate The controller uses this anticipat ed Control Temperature as the input to its heating control processes The result is that the heating output is increased or decreased early enough to avoid Control Temperature overshoot For most applications the default heating PA time value will provide the best control See the Project Ahead Algorithm section in the MicroTech Control Features portion of this manual for more information High Ambient Heating Lockout Programmable Parameters Menu lem Name High Ambient Heating Max OAT 55 F Lockout Setpoint High Ambient Heating Lockout Differential Heating will be disabled whenever the outdoor air tempera ture is greater than the high ambient heating lockout set point When this occurs the heating status state will be Off OAT Lockout if hea
105. on MCB1 will be continually lit and the alarm output will be energized The alarm output s LED indicates the state of the output On indicates energized and off indicates deener gized Both N O and N C contacts are available Typically the alarm output would be connected to some type of field supplied annunciator The method of alarm indication is set at Blink or Off at menu 25 Setting the Alarm Out Blink cause the amber sta tus LED on MCB1 to blink during alarm conditions Setting the Alarm Out Off causes the amber status LED to be off during alarm conditions The Alarm Out Off setting is used when communicating an alarm condition to a building man agement control system Note that the dirty filter alarms have a unique alarm indi cation Instead of flashing on and off in equal one half sec Page 20 OM 123 ond intervals the amber status LED and the alarm output LED will flash on for 9 10 second and off for 1 10 second when a dirty filter alarm occurs The controller s dirty filter alarms are caused by a pressure drop sensed by PS5 exceeding a field adjustable limit The limit is set at 0 60 WC pressure drop at the factory Adjustment at the sensor allow the limit to range from 0 17 to 5 00 WC pressure drop Priority The various alarms that can occur are prioritized according to their severity Three categories are possible faults prob lems and warnings Regardless of the alarm type a mes sage that identifies the alarm will
106. ondi tions have been met staging occurs as the controller attempts to equalize two running totals degree time above setpoint DTA and degree time below setpoint DTB Degree Time Above Setpoint DTA Every 10 seconds the controller measures the number of degrees the dis charge air temperature is above setpoint Each new mea surement is added to a running total called DTA Degree Time Below Setpoint DTB Every 10 seconds the controller measures the number of degrees the dis OM 123 Page 29 charge air temperature is below setpoint Each new mea surement is added to a running total called DTB During normal operation the number of stages will not change while the discharge air temperature is within the range above and below the discharge air cooling setpoint defined by the discharge air cooling dead band Typically during periods of constant cooling load cooling is alternate ly staged up and down between the two stages that cause the discharge air temperature to fluctuate closely above and below setpoint During periods of increasing or decreasing cooling load two or more consecutive stage ups or stage downs can occur Following are descriptions of the four pos sible consecutive staging changes Stage Up to Stage Down After a stage up occurs the discharge air temperature usually begins to drop toward set point DTA accumulates and continues to do so until the set point is reached When the discharge air temperat
107. only This alarm is manually cleared Current Sensor Problem The alarm occurs on dual motor units when the following three conditions exist for 30 seconds 1 Unit is in low speed motor operation 2 airflow switch flow and 3 Motor amp sensor reads zero amps As a result of the alarm the unit will only operate in High Speed until the alarm is manually cleared Cooling 6 5 4 3 2 or 1 Failure The Cooling Fail is caused be High Pressure Low Pressure or Frost switch in alarm position or a Motor Protector alarm indicated by the compressor contactor being off while MicroTech calls for compressor to be on or a Water Regulating Valve alarm The Water Regulating Valve alarm is determined by a Head Pressure setpoint If the Head Pressure remains below the edited Head Pressure setpoint by more than the dead band for more than 180 sec onds while compressor 1 is on compressors are disabled by the Water Regulating Valve alarm The highest priority alarm condition that exists for each compressor is displayed on the Keypad and monitor screens even if a compressor alarm is not the current active alarm The alarm priority is High Pressure highest Water Regulating Valve Frost Low Pressure Motor Protector lowest The affected compres sor is disabled by MicroTech Another compressor is not brought on automatically to replace the compressor The next compressor is brought on only if required by normal staging method The disabled com
108. or position at the end of this period becomes the new fully open or 100 value The actuator is then driven closed for 3 minutes The actuator position at the end of this period becomes the new fully closed or 0 position Inverters are not calibrated because fan operation may be required to speed up or slow down the inverters and running the inverter at full speed for calibration may cause damage to the duct work Keypad Display ID Parameter Menu tem Name 18 Duct Pressure Duct Sptz 1 00 WC Duct Setpoint Deadbd 0 08 WC Dead Band Duct Static Pressure Control Max Spt 2 00 WC Max Setpoint Reset No Reset Reset Method Position Mod Lim 0 040 WC Mod Limit Wait Time 20 Ten Wait Time Max Step 20 Ten In normal operation vanes or inverters are controlled to maintain the Duct Static Pressure at the desired setpoint using the Step and Wait function When the duct static pres sure gets too low the vanes inverters are opened speed ed up When the duct static pressure gets too high the vanes inverters are closed slowed down If two pressure sensors are provided the Duct Static Pressure equals the minimum of the two sensors Instead of normal operation the user may select control to a specific vane position or fan speed by selecting Reset Position in menu 17 In this situation the required vane position or inverter speed is provided via network com munication from another system or another MicroTech con
109. ormation can be found under menus 1 through 10 The following are available Unit status Cooling status Heating status Temperatures Pressures Fan Airflow status Airflow Mod differential pressure switch Economizer positions Operating Hrs position Misc Status The first three items are very useful because they summa rize the unit s status Using them you can quickly determine whether the unit is for example off starting up heating or cooling If heating or cooling is disabled for any reason you can find out why Following are descriptions of the possible unit status cooling status and heating status states Unit Status The unit status state menu 1 tells you the overall state that the unit is currently in At the keypad it can be displayed simply by pressing the Status key Except for the Calibrate every unit status state displayed is an operating state Operating States Operating states define the overall status of the unit under the various conditions that may occur during normal opera tion The following operating states are possible Off Start up Initialization Recirculate Post Heat Fan On Fan On Heating Economizer Cooling Morning Warm up Heating Unoccupied Economizer Unoccupied Cooling Unoccupied Heating For detailed information on these states see the Operating States and Sequences section in the Description of Operation portion of this manual Calibrate The Cali
110. ow has been proven High refrigerant pressure low refrigerant pressure frost switch in alarm position or a compressor motor protector trip condition occurred in refrigeration circuit 6 High refrigerant pressure low refrigerant pressure frost switch in alarm position or a compressor motor protector trip condition occurred in refrigeration circuit 5 High refrigerant pressure low refrigerant pressure frost switch in alarm position or a compressor motor protector trip condition occurred in refrigeration circuit 4 High refrigerant pressure low refrigerant pressure frost switch in alarm position or a compressor motor protector trip condition occurred in refrigeration circuit 3 Amp Sensor Prob Cooling 6 Fail Auto Cooling 5 Fail Auto Cooling 4 Fail Auto Cooling 3 Fail Auto Cooling 2 Fail High refrigerant pressure low refrigerant pressure frost switch in alarm position or a compressor motor protector trip condition occurred in refrigeration circuit 2 High refrigerant pressure low refrigerant pressure frost switch in alarm position or a compressor motor protector trip condition occurred in refrigeration circuit 1 EWT Sensor Prob Entering water temperature sensor failed Zone temperature sensor failed when it was not control temp or no return sensor present Return air temperature sensor failed while it was no
111. p again on the same day you must use an NMP schedule or an external time clock NMP Scheduling If the unit controller is included in a MicroTech network with a Network Master Panel an NMP schedule can be used instead of the internal schedule To use an NMP schedule the unit controller s Network Master Panel Schedule para meter must be set to the desired NMP schedule number When the control mode menu 11 is set to Auto the NMP schedule you selected will start and stop the unit Using an External Time Clock If desired an external time clock can be used to schedule unit operation In this case all internal daily schedules must be set to 00 00 00 00 this is the default setting When the control mode menu 11 is set to Auto the external time clock will start and stop the unit Holiday Scheduling Programmable Parameters Keypad Display ID 22 Schedule Hol 00 00 00 00 Holiday Schedule NMP Sched No N A Network Master Panel Schedule 24 Holiday Date Date Dec 25 Holiday Date Dur 1 Day s Holiday Date Duration You can schedule special operating hours for up to 14 holi day periods by using the controller s holiday scheduling fea ture The wildcard character in the above table could be any number between 1 and 14 Whenever a holiday date occurs the controller will use the Holiday Schedule s start and stop times for the number of successive days specified by the associated holiday dat
112. ponse to the Control Temperature s deviation from the zone heating setpoint If the Control Temperature is less than the zone heating setpoint by more than the zone heating dead band the Discharge Air Heating setpoint is raised slightly If the Control Temperature is greater than the zone heating setpoint by more than the zone heating dead band the Discharge Air Heating setpoint is lowered slightly If the Control Temperature is within the range above and below the zone heating setpoint defined by the zone heating dead band the Discharge Air Heating setpoint is held con stant Regardless of the zone heating load the Change function will not be allowed to adjust the Discharge Air Heating setpoint outside the range defined by the minimum and maximum Discharge Air Heating setpoints The Change function uses four parameters 1 zone heating dead band 2 setpoint mod limit 3 setpoint wait time and 4 setpoint max step For most applications the default values for these parameters will provide the best control For more information see the Change Algorithm section in the MicroTech Control Features portion of this manual Note The controller will not allow you to set the minimum Discharge Air Heating setpoint above the zone heating set point This restriction will ensure better zone temperature control during heating operation Project Ahead The Project Ahead algorithm works to prevent the Control Temperature from
113. pressor is skipped as the number of stages increases and decreases so that a change in cooling capacity is not delayed due to a disabled com pressor being called for High Pressure and Water Regulating alarms require man ual clearing Other alarms are cleared automatically when the alarm condition disappears and the stage timer expires This will keep the compressor off for at least the stage timer However manual clearing is required if the same alarm occurs three times between 2 00 am of one day and 2 00 am of the next day Compressors that are currently disabled due to alarm conditions are shown in Menu 28 of the keypad To release all disabled compressors press the clear key at the first item of Menu 28 To release a single compressor for operation press the clear key at the item that displays that compressor The compressor will go back into alarm if the alarm condition still exists EWT Sensor Problem The EWT Sensor Problem occurs when the entering water temperature sensor is shorted or open The alarm disables the water cooled economizer The alarm clears automatical ly when conditions disappear Zone Sensor Problem If the zone temperature sensor SPT1 fails the Zone Sensor Problem alarm will occur As a result the unit will continue to operate but the night setback night setup and zone reset features will be disabled In addition if the Control Temperature source had been selected to be the zone sensor the controller
114. r more information see the Determining Unit Status section in the Operator s Guide portion of this manual Operating Hours Menu 9 Operating Hrs provides the operating hours for each compressor cooling economizer heating and over ride Miscellaneous Status Menu 10 Misc Status tells you heat output outdoor damper position head pressure percent humidity and dew point temperature OM 123 Page 7 Table 2 Status Menus MEL A EENEG el we wee 099 Ge Se Range 1 n Menu em Unit Status 11 Contro Mode current control mode Off Unoccupied Off Fan Switch Off Network Off Manual Off Service Off Alarm Calibrate Start Requested Startup Initial Recirculate Fan On Heating Morning Warm Up Fan On Htg Stg Post Heat Economizer Cooling Heating Stage MWUP Htg Stg Fan On Heating Cooling Stage Unoccupied Heat Unocc Htg Stg Unoccupied Cool Unocc Clg Stg Unocc Economizer Dehum Fan On Dehum Heating Dehum Mwup Heat Dehum Fan On Ht Dehum Post Heat Dehum Cooling Temperatures Cntl Temp SF Same as CT sensor 12 Heat Cool Cntl Temp Supply Air F 0 255 F 13 Clg Control Ent Water EE 0 255F 13 Clg Control Waterflow Lvg Water F 0 255 F Fa
115. r shuts down the fans and drives open the economizer valve outdoor air dampers or vanes when three minutes have elapsed the controller records the feedback value of the actuator as equivalent to its fully open position The controller then dri ves the actuator closed When three minutes have elapsed the controller records the feedback value of the actuator as equivalent to its fully closed position Since there is no air flow through the unit the controller records the input volt ages of all connected pressure transducers as equivalent to 0 000 W C After the Calibrate procedure is complete the controller shuts down the unit and places it into the Off Manual control mode The unit can be restarted by changing the control mode Note Inverters are not calibrated Page 18 OM 123 Service Mode Programmable Parameters Keypad Dispiay ID Meu iubes Mode Normal There are two service modes that can be selected only at the keypad with the Service Mode parameter Shutdown and Normal When the Shutdown service mode is selected the unit is placed into the Off Service operating state In the Off state the unit is shut down For more information on operat ing states see the Operating States and Sequences sec tion of this manual Unlike the Off Manual contro mode the Shutdown ser vice mode cannot be overridden by an operator at a remote PC or remote keypad The only way to return the unit to nor mal operation
116. re delta between EWT and MAT is less than the differential Table 7 Operating States for 100 Outdoor Air Outside Supply Waterside Mechanical VAV Occupied Operating State z 8 Heat q Unit Status Air Fen Economizer Enabled Cooling Heat Output Damper Airflow Waterflow Enabled Output K6 K15 Off O Closed 0 Flow Off Open Q Open Start Up Initialization Open Minimum Off Open Closed Fan On Open Modulating Off Closed Closed O Fan On Heating Open Modulating Off Closed Closed amp Economizer Open Modulating Modulating Closed Closed Cooling Open Modulating Off or Open Closed Closed Heating Open Modulating Off Open Closed Unoccupied Econ Open Modulating Modulating Closed Closed Unoccupied Cooling Open Modulating Off or Open Closed Closed O Unoccupied Heating Open Modulating off Closed Closed Notes 1 The outside air damper will close 3 minutes after the unit enters the Off state 2 The Fan On output will open 3 minutes after the unit enters the Off state 3 Waterside Economizer will be Off if the temperature delta between EWT and MAT is less than the setpoint at menu 18 EWT Diff 4 This state is possible only on units that have a waterside economizer 5 This state is not applicable to cooling only units OM 123 Page 23 Displaying the Operating State The current unit status menu 1 shown is the current oper ating state At the keypad you can display the current unit status simply by pressing
117. riptions of the various alarms that could occur in CAV ZTC self contained units Note that some alarms are detected by optional equipment for example the freezestat or smoke detectors If the unit is not equipped with the optional control the associated alarm cannot occur Note The cause of a manual reset alarm should be investigated and eliminated before the unit or any disabled equipment in it is placed back into service Faults Freeze Shutdown The Freeze Shutdown alarm will occur whenever the option al freezestat s FS1 contacts open as a result of detecting an abnormally low water coil temperature when the fan has been running for more than 60 sec If the Freeze Shutdown alarm occurs the MicroTech con troller will shut down the fans close the outdoor air dampers open the waterside economizer open the chilled water and heating valves The unit will remain shut down until the Freeze Shutdown alarm is manually cleared Smoke Shutdown The Smoke Shutdown alarm will occur whenever the con tacts of the optional smoke detector SD1 open If this alarm occurs the unit will be immediately shut down The unit will remain shut down until the smoke detector is manually reset and the Smoke Shutdown alarm is manually cleared To determine the locations of the smoke detectors refer to the Control Locations section of applicable model spe cific installation manual see Table 1 Duct High Limit The Duct High Limit alarm will occ
118. s 23 Operating State Descriptions 24 Sequence Charts 20 0 0 25 Start up Control 26 Before Gtart up eee eee 26 Fan Start up Mixed or 100 Return Air 26 Fan Start up 100 Outside Air 26 Heat Cool Changeover 000 26 Temperature Control 26 ECOHOMIZED sioe ree es oen 27 Temperature Control o oooooooooo o 27 Changeover Method Waterside 28 Changeover Method Airside 28 Transition Economizer to Mechanical Cooling 29 Bypass Valve sasra aaa naa We na nn nn 29 100 Outside Air Units 29 Cooling Multistage 29 Temperature Control 29 Low EWT Cooling Lockout 31 Setpoint Reset oooooooooocoomoo 31 Air Modulation 000200 00 0 33 A arga A a a AA 33 VIV Inverters 0 ee 33 Cooling Modulating SCP units only 34 Temperature Control 34 Low Ambient Cooling Lockout 34 Setpoint Reset uos e REGIE 34 Heating Multistage 35 Temperature Control 35 High Ambient Heating Lockout 35 Morning Warm up Control e EE E 35 Discharge Air Low Limit Control 36 Heating Modulating oo 36 Temperature Control 36 High Ambient Heating Lockout 37 Morning Warm up Control 37 Discharge Air Low Limit Control 37 Heating
119. sage for each compressor For more information see the Alarm Monitoring section in the Operator s Guide portion of this manual Table 4 Alarm Menus Curr Alarm Prev Alarm Name Default Shown Alarm Message 59 er ooo Destination None Filter Dirty Air Flow Warning Econo Stuck No Water Flow Heat Fail Mixed T Prob OAT Prob Return T Prob Zone T Prob Supply T Prob EWT Prob Cooling 1 Fail Cooling 2 Fail Cooling 3 Fail Cooling 4 Fail Cooling 5 Fail Cooling 6 Fail AmpSensor Prob VelSensor Prob LoSpd Fan Prob HiSpd Fan Prob Freeze Problem Vanes Stuck Fan Fail Low Supply T High Supply T Hi oh Return T pply T Fail hr mn mm dd yy Alarm Message Mixed T Fail Gane as Curr Alarm O hr mn mm dd yy Prev Alarm Alarm Message Same as Curr Alarm 9 hr mn mm dd yy Prev Alarm Alarm Message Same as Curr Alarm hr mn mm dd yy Prev Alarm Alarm Message Same as Curr Alarm O hr mn mm dd yy Prev Alarm Alarm Message Same as Curr Alarm Prev Alarm Alarm Message Same as Curr Alarm O hr mn mm dd yy Prev Alarm Alarm Message Same as Curr Alarm
120. since the Contro Temperature is likely well above the cooling enable setpoint menu 12 cooling is enabled and disabled only by the zone tempera ture For more information see the Economizer and Cooling Multistage or Cooling Modulating sections as applicable Head Pressure Control Programmable Parameter IEA A AL gt AA 19 Head Pressure Setpoint 160 psi Dead Band 10 psi Mod Limit 30 psi Wait Limit 10 Sec Max Step 10 Sec A water regulating valve WRV modulates the flow to the condenser in response to a refrigerant pressure signal from circuit 1 at Input 15 Output 16 closes the WRV when the pressure gets too low and output 17 opens the WRV when the pressure gets too high The WRV function operates only when circuit 1 is on With circuit 1 down compressor operation is allowed for remaining circuits without head pressure control if condenser water temperature is below 55 F Head pressure control is only provided on units that do not have a waterside economizer and do not have an External Reset Building Static Pressure Control Programmable Parameter Keypad Display ID 17 Bldg Pressure Zone Spt 0 050 WC Min Pos 60 Min Speed 60 Deadbd 0 008 WC Mod Lim 0 040 WC Wait Time 20 Ten 20 Ten Max Step Page 42 OM 123 This feature is provided primarily to maintain building static pressure for 10096 outside air units
121. sition feedback indicates that the outside air dampers are less than 50 open at the end of the Start Initial period for units with 100 outside air control Supply Vane Stuck The Variable Inlet Vanes feedback indicates that the Vanes are more than 25 open and the unit has been off for more than three minutes As a result the unit will be shut down It will remain shut down until the Supply Vane Stuck alarm is manually cleared Problems Freeze Problem The Freeze Problem alarm will occur whenever the optional freezestat s FS1 contacts close as a result of detecting an abnormally low water coil temperature while the fans are off If the Freeze Problem alarm occurs the MicroTech con troller will keep the fans off keep the outdoor air dampers closed open the waterside economizer open the chilled water and heating valves Whenever the freezestat opens the Freeze Problem alarm automatically clears This feature protects the coil s and allows the system to start normally after a cold night High Speed Fan Problem The High Speed Fan Problem will occur if no air flow is sensed after two minutes of operation The unit is turned off and restarted normally except that it operates at low speed fan only This alarm is manually cleared Low Speed Fan Problem The Low Speed Fan Problem will occur if no air flow is sensed after two minutes of operation The unit is turned off and restarted normally except that it operates at high speed fan
122. t in which they are used and the temperature change is sig nificant Dehumidification Programmable Parameter Keypad Display ID 19 Humidity Ctrl Control None Enabled Occupied Sensor Return Timer 10 Min Humidity Spt 50 Humidity Db 2 DewPt Spt 50 F DewPt DB 2 F Min Stages 2 Max Stages 4 The dehumidification function is available on all units to reduce the humidity in the space by cooling the discharge air low enough to wring moisture out of it and to reheat the dis charge air to maintain the desired temperature An analog sensor is mounted in either the space or return duct to sense Relative Humidity The sensor is connected to input 15 so dehumidification can not be used with either External Reset or Head Pressure Control The Relative Humidity and a calculated Dewpoint are both displayed on keypad menu 10 Either may be used for control Dehumidification operation is initiated when Humidity Control is set to either Relative Humidity or Dewpoint and that value rises above the corresponding setpoint by more than its dead band Humidity control is disabled if cooling is disabled or if heating is disabled for any reason except high OAT A unit in the unoccupied state will be started when Dehumidification is initiated only if the Enabled entry on the keypad is set to Always During Dehumidification economizer operation is dis abled During Dehum
123. t Up Control A self contained unit could start for a variety of reasons For example an internal or network schedule an external time clock a tenant override command or night setback control could cause unit start up Regardless of the reason it starts the unit will always go through a controlled start up sequence before allowing temperature control to begin Before Start Up Programmable Parameters Keypad Display ID Parameter Menus Sem Cd Name Initial 180 Sec Start Up Initialization When the controller receives a start up command its oper ating state quickly changes from Off to Start Requested to Start Up Initialization During Start Up Initialization the Fan On output is closed to indicate that the fans are about to start and the supply fan inlet vanes are modulated to a min imum position The minimum vane position assures that the fans will start unloaded while allowing airflow status to be proven quickly The duration of the Start Up Initialization state is defined by the Start Up Initialization Time parameter Its default value is three minutes Caution The Start Up Initialization Time should be set so that the Start Up Initialization state lasts long enough to allow any field supplied equipment that is controlled by the Fan On output to prepare for fan operation Fan Start Up Mixed Air or 100 Return Air Units Programmable Parameters Parameter Name Keypad Display ID Menu Initial 180 Sec _
124. t the Contro Temperature source Outside air temperature sensor failed Mixed air temperature sensor failed Supply air temperature exceeds Mixed air temperature by 60 F Safety lockout condition occurred in electric heat Lack of water flow is indicated by an open water flow switch Economizer not fully closed during unit shutdown or not fully open during mechanical cooling operation with conditions acceptable for economizer operation Airflow indicated while fans were off Pressure drop input across filter is in the alarm position O Zone Sensor Prob Ret Sensor Prob OAT Sensor Prob Mix Sensor Prob High Temp Rise Heat Fail No Water Flow Economizer Stuck Air Flow Warning Filter Dirty Notes 1 A manual reset is required at smoke detector SDI before the Smoke Shutdown alarm can be cleared 2 The Zone Sensor Problem alarm will occur if the Zone Temperature sensor fails while it is not the Control Temperature source or if there is a Return Temperature Sensor 3 The Zone Sensor Fail alarm will occur only if it is the selected Control Temperature source and there is no Return Air Temperature sensor 7 j Previous Alarm Buffer Disp lay ing Alarms When the current alarm is cleared or replaced by a higher Programmable Parameters priority alarm it is stored in the previous alarm buffer menu 27 The previous alarm also includes the time and date of occurrence The previous alarm buffer holds the last 8 alarms
125. t will continue to operate but the high ambient heating lockout and OAT reset will be disabled When the alarm condition is gone the OAT Sensor Problem alarm will automatically clear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller To determine the location of the OAT sensor refer to the Control Locations section of applicable model spe cific installation manual see Table 1 Mixed Air Sensor Problem If the mixed air temperature sensor MAT fails the Mixed Sensor Problem alarm will occur As a result the waterside economizer will be disabled When the alarm condition is gone the Mixed Sensor Problem alarm will automatically clear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller To determine the location of the MAT sensor refer to the Control Locations section of applicable model spe cific installation manual see Table 1 High Temp Rise The High Temperature Rise alarm occurs when unit has staged electric heat and discharge air temperature equals or exceeds mixed air temperature by 60 F The electric heat is disabled by MicroTech The High Temperature Rise alarm requires a manual reset Heating Failure The Heat Fail alarm is applicable only to uni
126. tep and Wait control can also be speeded up by decreasing the wait time Remember that the max step value must always be less than or equal to the wait time value The dead band affects the tightness of control You can set it to a lower value to keep the controlled variable closer to its setpoint However if the dead band is set too low it can cause hunting in some situations Note Some Step and Wait control loops use position as the controlled variable For example this type of control is used to maintain the economizer dampers at the minimum position setpoint The position Step and Wait parameters are available at a PC equipped with Monitor software but not at the keypad Typically these position parameters should never require any adjustment 612 553 5330 e Printed on recycled paper containing at least 10 post consumer recycled material
127. than the discharge air cooling dead band value The transition can also occur if 1 the econo mizer has been active for at least 10 minutes and 2 the dis charge air temperature is above the discharge air cooling setpoint by an amount greater than or equal to the econo mizer dead band value plus 2 F This backup feature will ensure that cooling is provided if the economizer gets stuck If the entering waterside economizer temperature airside economizer enthalpy is low when mechanical cooling is activated Cooling or Unoccupied Cooling state the water side economizer valve airside economizer dampers will be driven to full open They will remain there until either mechanical cooling is no longer necessary or the entering water outdoor air is no longer suitable for free cooling If mechanical cooling is no longer necessary the economizer will resume modulation During occupied and unoccupied operation the water valve will close if entering water is not suitable for free cooling During occupied operation the out side air dampers will go to the current minimum position set ting if the outdoor air is no longer suitable for free cooling During unoccupied operation the outside air dampers will close if the outdoor air is no longer suitable for free cooling For more information on mechanica cooling operation see the Cooling Multistage or Cooling Modulating sec tion as applicable Page 28 OM 123 Changeover Method for Wat
128. the heating state because the overall heating load is satisfied When this occurs during occupied periods the controller will enter Fan On state See Discharge Air Low Limit Control below for more information on Fan On Heating High Ambient Heating Lockout Programmable Parameters Menu tem Name Hig Control Max OAT 55 F gt Lockout Setpoint High Ambient Heating Lockout Differential Heating will be disabled whenever the outdoor air tempera ture rises above to the high ambient heating lockout set point When this occurs the heating status state will be Off OAT Lockout if heating is not disabled for some other rea son When the outdoor air temperature drops below the high ambient heating lockout setpoint by more than the high ambient heating lockout differential heating operation will be enabled again The default value of this differential is 3 F PC adjustable only Setpoint Reset Programmable Parameters Keypad Display ID Parameter wem 7 Name 14 Htg Control Setpoint 100 F Discharge Air Heating Min Spt 60 F Minimum Discharge Air Heating Setpoint Heating Reset Type Reset Sensor Minimum Heating Setpoint Max Spt O 64 F Reset Sensor Maximum Heating Setpoint By automatically varying the discharge air temperature to suit the building s heating load discharge air temperature reset can make some VAV systems more energy efficient A variety of reset strategies are ava
129. ting is not disabled for some other rea son When the outdoor air temperature drops below the high ambient heating lockout setpoint by more than the high ambient heating lockout differential heating operation will be enabled again The default value of this differential is 3 F PC adjustable only Morning Warm Up Control Programmable Parameters Menu tem Name 12 Heat Cool Heating spt 68 F Zone Heating Setpoint 0 2 Max MWUP 90 Min Maximum Morning Warm Up Time On mixed air units morning warm up operation occurs just after the recirculation state when the Control Temperature is less than the zone heating setpoint minus the zone heating dead band Morning Warm up is similar to the Heating state the only difference is that the outside air dampers are held shut dur ing Morning Warm up The unit will remain in the Morning Warm up state until either the Control Temperature equals the zone heating setpoint or the duration of morning warm up operation exceeds the maximum morning warm up time setting default is 90 minutes whichever happens first In either case since the Control Temperature will not have risen above the zone heating setpoint by more than the zone heating dead band when this occurs the controller will enter the Heating state OM 123 Page 35 The maximum morning warm up time parameter is pro vided to ensure that the required minimum ventilation air is being supplied after a know
130. tpoint Max Spt 65 F Reset No Reset Min Spt 90 F Max Spt 70 F A variety of reset strategies are available some require field wiring Because they are programmable you can change or eliminate reset strategies as desired When a reset strategy is operational it will automatically change the discharge air cooling setpoint as required You can display the current setpoint but the controller will not let you change it If you do not want reset set the cooling reset type to No Reset default The controller will then allow you to enter a fixed discharge air cooling setpoint The following discharge air cooling reset methods are available Space temperature Return air temperature Outdoor air temperature Airflow External 1 5 VDC or 4 20 mA signal Regardless of the reset method the minimum discharge air cooling setpoint and maximum discharge air cooling setpoint define the range of possible discharge air setpoints The above reset methods are identical to the ones avail able for use with multistage mechanical cooling For more information see Setpoint Reset in the previous Cooling Multistage section Heating Multistage with Zone Control Temperature Control Programmable Parameters Keypad Display ID Parameter Men f tem Name 12 Heat Cool Heating spt 68 F Zone Heating Setpoint Ho Dead Band 7 F Zone Heating Dead Band Htg PA 8 Min Heating PA Ti
131. trol Locations section of applicable model spe cific installation manual see Table 1 Supply Air Sensor Failure If the supply air temperature sensor SAT fails the Sup Sensor Fail alarm will occur As a result the unit will be shut down lt will remain shut down until the Sup Sensor Fail alarm is manually cleared Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 608 MicroTech Self contained A r Conditioning Unit Controller To determine the location of the SAT sensor refer to the Control Locations section of applicable model spe cific installation manual see Table 1 High Return Temperature If the return air temperature exceeds or equals the high return temperature limit setting menu 15 while the unit is operational the High Return Temp alarm will occur As a result the unit will be shut down It will remain shut down until the High Return Temp alarm is manually cleared High Supply Temperature If the discharge air temperature exceeds or equals the high supply temperature limit setting menu 15 while the unit is operational the High Supply Temp alarm will occur As a result the unit will be shut down It will remain shut down until the High Supply Temp alarm is manually cleared Low Supply Temperature If the discharge air temperature equals or drops below the low supply temperature limit setting menu 15 while the unit is operational the Low Suppl
132. troller such as an RMC panel The unit control does not allow this setpoint to be set below the minimum value of 1796 A separate set of Step and Wait parameters that are not changeable by the user is provided for this type of control Building Static Pressure Control Menu Hem O Name Zone Spt 0 050 WC Duct Setpoint Min Pos 60 Dead Band 18 Bldg Pressure Min Speed 60 96 Max Setpoint Deadbd 0 008 WC Dead Band Mod Limz 0 040 WC Mod Limit Wait Timez 20 Ten Wait Time Max Step 20 Ten Max Step The Variable Inlet Vanes or Inverters may be controlled based on Building Static pressure instead of Duct Pressure This feature is provided primarily to maintain building static pressure for 10096 outside air units with variable exhaust The building static pressure sensor input replaces the first duct static pressure sensor input Step and Wait is used to control the vanes or inverters A minimum position of the Vanes or Inverters insures that sufficient ventilation is main tained even if that means that the building static pressure gets higher than desired When the building static pressure gets too low the vanes inverters are opened speeded up When the building static pressure gets too high the vanes inverters are closed slowed down OM 123 Page 33 Cooling Modulating SCP units only Temperature Control Programmable Parameters Keypad Displa
133. ts equipped with electric heat When the Heat Fail input is in the alarm posi tion the unit will continue to operate but one or two stages of electric heat will be disabled The Heat Fail alarm will clear automatically when the condition disappears Page 46 OM 123 No Water Flow Lack of water flow is indicated by an open water flow switch or a network signal Cooling provided by compressors or waterside economizer is disabled The only cooling that may be available is provided by an airside economizer The No Water Flow alarm will clear automatically when the water flow input is in the flow position Warnings Economizer Stuck On units equipped with an economizer the Economizer Stuck alarm will occur if either of two alarm conditions exists 1 the economizer position 1096 and unit has been off for more than three minutes or 2 Economizer position 90 and unit has been in mechanical cooling with conditions acceptable for economizer operation for more than three minutes Unit operation will not be affected by this alarm but because stuck dampers could be a serious problem during cold weather the Economizer Stuck alarm must be manual ly cleared Note that the controller monitors the economizer actuator s position and that this value is available for display menu 6 If the economizer appears to open and close completely but the monitored position does not indicate it try having the controller perform the Calibrate procedur
134. ts rising again because the load is increasing Point 7 The discharge air temperature is again above setpoint by more than the dead band Since the interstage timer expired at Point 6 cooling is staged up As a result both DTA and DTB are zeroed out and the interstage timer is reset The discharge air temperature continues to rise however because the cooling load is still increasing Point 8 The interstage timer expires Since the dis charge air temperature is still above the dead band range another stage up occurs As a result DTA Area K is again zeroed out and the interstage timer is reset The cooling load has leveled out and thus the discharge air temperature drops Point 9 The interstage timer expires at nearly the same time that DTB Area M becomes equal to DTA Area L As a result the interstage timer is reset and DTA is subtracted from both DTA and DTB This zeros out both DTA and DTB since they are equal Figure 9 Typical Compressorized Cooling Operating Sequence Stage Up C D E F o ke 3 4 A TI o a 5 f Nr lt gt Q a d NoAction Yo A B 1 Stage Down Interstage 4 Timer Not t Expired Time Minutes Nearest SAT Compressor Staging This method is useful if the load of all the spaces can be maintained with the SAT slightly above the SAT setpoint Except during unit shutdown a stage change can only occur 1 after the cooling interstage timer has
135. ture and pressure con you should read and understand the sections that apply to trol The Operating States and Sequences section provides your unit an overall description of unit operation The subsequent sec For detailed information on the Step and Wait function tions provide detailed descriptions of the various control which controls the units modulating valves and dampers processes and how their setpoints and parameters affect see the MicroTech Control Features portion of this manual Operating States and Sequences Operating states define the current overall status of the Self Heating system status contained system With a single keystroke you can display Airside and waterside economizer status the operating state and thus quickly assess the unit s condi Mechanical cooling system st tus tion Each operating state summarizes the following infor Occupied output status mation VAV Heat output status Supply fan status Tables 6 and 7 show the operating states and the status e Outdoor air damper status information Table 6 is for Mixed Air or 100 Return Air Unit Supply fan inlet vane status and Table 7 is for 10096 Outside Air Units Table 6 Operating States for Mixed Air or 100 Return Air Operating State Airside Waterside Heat Mechanical VAV Occupied Unit Status Economize Economizer Enabled Cooling Heat Output
136. ugh for free cooling but not cool enough to prevent mechanical cooling compressorized or chilled water the cooling status will be All Cooling Allowed in this state the unit will use the economizer or mechanical cooling as required to maintain the cooling setpoints Heating Status The heating status menu 8 tells you whether heating is enabled or disabled H heating is disabled the reason is given Following are descriptions of the various heating sta tus states S Off OAT Lockout When the outside air is too warm for heating operation the heating status will be Off OAT Lockout In this state the unit s heating equipment will be disabled Off Unoccupied When the unit is shut down by a scheduling function all heating will be disabled and the heating status will be Off Unoccupied Network Disable If the heating status is Network Disable it means that a net work command has disabled all heating Switch Disable If the heating status is Switch Disable it means that the Heat Enable input is open All heating will be disabled during the Switch Disable state This status also appears when heat is not installed Manual Disable If the heating status is Manual Disable it usually means that the control mode menu 11 has been set to one of the fol lowing Off Manual Occ Cool Only Occ Fan Only or Calibrate The Manual Disable heating state can also occur if the controller is in the Shutdown service mode menu 25 All
137. umn lists all possible values for each adjustable field Following are brief descriptions of the Control category menus Control Mode Menu 11 Control Mode allows you to set the unit for auto matic or manual operation For more information see the Auto Manual Operation section in the Operator s Guide portion of this manual Heat Cool Menu 12 Heat Cool contains zone temperature parame ters that are used to control the unit s heating and cooling equipment For more information see the Description of Operation portion of this manual Cooling Control Menu 13 Clg Control contains parameters that are used to maintain cooling discharge air temperature control For more information see the Description of Operation portion of this manual Heating Control Menu 14 Htg Control contains parameters that are used to maintain heating discharge air temperature control For more information see the Description of Operation portion of this manual Alarm Limits Menu 15 Alarm Limits contains adjustable supply and return air temperature limits that are used to generate alarms For more information see the Alarm Monitoring section in the Operator s Guide portion of this manual Unoccupied Heating Cooling Menu 16 Unocc Htg Clg contains the unoccupied heating night setback and unoccupied cooling night setup set points that are used to start and run the unit at night wh
138. up Programmable Parameters Keypad Display ID Parameter Men Name Unocc Htg Clg Cooling Spt 85 F Night Setup Setpoint BESSERES Neni Sewp Diherental If a zone temperature sensor is connected to the controller night setup cooling control is available Following s a description of operation If the zone temperature rises to night setup setpoint when the unit is in the Off Unoccupied state the unit will start up and run If the unit has an economizer and free cooling is available the controller will enter the Unoccupied Economizer state after Recirculate Note that there is no minimum outside air damper position control during the Unoccupied Economizer state If economizer is either not available or not cool enough to maintain the current discharge air cooling setpoint the con troller will activate mechanical cooling as it enters the Unoccupied Cooling state If free cooling is available the economizer will be wide open during Unoccupied Cooling If free cooling is not available the economizer will be fully closed during Unoccupied Cooling When the zone temperature drops below the night setup setpoint by more than the night setup differential the con troller will shut down the fans and return to the Off Unoccupied state The default value of this differential is 3 F After the unit is started cooling equipment control during night setup cooling operation is similar to that during occu pied operation However
139. ur whenever the contacts of the duct high pressure limit control DHL open If this alarm occurs the unit will be immediately shut down The unit will remain shut down until the Duct High Limit alarm is manually cleared Zone Sensor Failure If the zone temperature sensor SPT1 fails while it is the selected Control Temperature source on a 100 outdoor air unit the Zone Sensor Fail alarm will occur As a result the unit will be shut down It will remain shut down until the Zone Sensor Fail alarm is manually cleared The Zone Sensor Fail alarm cannot occur on a mixed air or 100 return air unit information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller Mixed Air Sensor Failure If the Mixed air temperature sensor MAT fails while it is the selected Control Temperature source the Mat Sensor Fail alarm will occur As a result the unit will be shut down It will remain shut down until the Mat Sensor Fail alarm is manu ally cleared Note that the unit can be quickly restarted by selecting another Control Temperature source before clear ing the alarm Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller To determine the location of the Mat sensor refer to the Control Locations section of appli
140. ure drops below setpoint DTA stops accumulating and DTB starts accumulating When DTB equals or exceeds DTA the stage down will occur but only if the interstage timer has expired and the discharge air temperature is below the set point by more than the dead band If either staging con straint has not been met DTB will continue accumulating After the stage down occurs the DTA value is subtracted from both DTA and DTB As a result DTA is zeroed out and DTB is either zeroed out or largely reduced The interstage timer is reset and degree time accumulation resumes Stage Down to Stage Up After a stage down occurs the discharge air temperature usually begins to rise toward setpoint DTB accumulates and continues to do so until the setpoint is reached When the discharge air temperature rises above setpoint DTB stops accumulating and DTA starts accumulating When DTA equals or exceeds DTB the stage up will occur but only if the interstage timer has expired and the discharge air temperature is above the set point by more than the dead band If either staging con straint has not been met DTA will continue accumulating After the stage up occurs the DTB value is subtracted from both DTB and DTA As a result DTB is zeroed out and DTA is either zeroed out or largely reduced The interstage timer is reset and degree time accumulation resumes Stage Up to Stage Up If the cooling load increases after a stage up occurs the discharge air t
141. ure is below the zone heating set point by more than the zone heating dead band or 2 the discharge air temperature is below the Fan On Heating Spt Stage Down Action A stage down can occur for two reasons 1 the Control Temperature is above the zone heating setpoint by more than the zone heating dead band or 2 the discharge air temperature is above the maximum Discharge Air Heating setpoint Note that a stage down from stage 1 to stage O can occur During stage O operation all heating stages are off but the controller remains in the heating operating state After the interstage timer expires another stage down would cause the controller to leave the heating state There is one exception to the above interstage timing constraint If the discharge air temperature drops below the minimum heating discharge air setpoint by more than the Discharge Air Heating dead band during stage O operation the stage up transition to stage 1 will occur regardless of the interstage timer or Control Temperature If contradictory stage change conditions exist when the heating interstage timer expires the controller will stage heating up or down according to the minimum and maximum Discharge Air Heating setpoints For example if the dis charge air temperature is below the minimum Discharge Air Heating setpoint stage up condition when the Control Temperature is above the zone heating setpoint by more than the zone heating dead band stage down conditi
142. very useful for mixed air applications that require larger amounts of minimum outside air to accommodate for example indoor air quality requirements If the outdoor air temperature is very cold the mixed air tem perature could become unacceptably cold in these units Because the economizer dampers maintain their minimum position during Fan On Heating minimum ventilation requirements are never violated Fan On Heating is essen tial for 100 outdoor air applications in cold climates Heating Modulating with Zone Control Temperature Control Programmable Parameters Keypad Display ID Parameter Name Zone Heating Setpoint 12 Heat Cool Heating spt 68 F Htg Dead Band 1 F Htg PA 8 Min Mod Limits 10 F Wait Time 1 Min Setpoint Wait Time Max Step 10 Setpoint Max Step Supply air heating Setpoint 14 Htg Control Setpoint 100 F Min Spt 60 F Minimum Supply air heating Setpoint Max Spt 120 F Maximum Supply air heating Setpoint Sig Timerz 5 Min Dead Band 1 F Supply air heating Dead Band Mod Limit 60 F Wait Time 30 See If heating is enabled see note below and there is a zone heating load the controller will activate the unit s modulating heating equipment as it enters the Morning Warm up Heating or Unoccupied Heating state This will occur when the Control Temperature is below the zone heating setpoint by more than the zone heating dead band value Following is a description of oper
143. will automatically change it to the return air sensor When the alarm condition is gone the Zone Sensor Problem alarm will automatically clear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller For more information on the emergency occupied mode see the Unoccupied Control section Note If SPT1 is not connected to the controller or if you want to disable the Zone Sensor Problem alarm set the space sensor present flag to No menu 25 OM 123 Page 45 Return Air Sensor Problem If the return air temperature sensor RAT fails while it is not the selected Control Temperature source the Ret Sensor Problem alarm will occur As a result the unit will continue to operate but the High Return Temp alarm and reset based on RAT will be disabled When the alarm condition is gone the Ret Sensor Problem alarm will automatically clear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 608 MicroTech Self contained Air Conditioning Unit Controller To determine the location of the RAT sensor refer to the Control Locations section of applicable model spe cific installation manual see Table 1 Outdoor Air Sensor Problem If the outdoor air temperature sensor OAT fails the OAT Sensor Problem alarm will occur As a result the uni
144. y ID Menu lem Setpoint 55 F Parameter Name Supply air Cooling Setpoint Stg Timer 5 Min Cooling Interstage Timer Dead Band 1 F Supply air Cooling Dead Band Supply air Cooling Mod Limi Supply air Cooling Wait Time Supply air Cooling Max Ste Project Ahead Timer On SCP units the chilled water coil replaces the waterside economizer coil If the unit is equipped with an air econo mizer and the conditions are suitable for free cooling the unit controller will attempt to satisfy the cooling load by using economizer before using mechanical cooling See the Economizer section above If the unit is not equipped with an economizer the controller will activate mechanical cool ing whenever cooling is required If mechanical cooling is enabled see note below and economizer is either not available or not cool enough to maintain the current discharge air cooling setpoint the con troller will activate mechanical cooling During occupied peri ods the operating state will be Cooling During unoccupied periods the operating state will be Unoccupied Cooling When mechanical cooling is required the controller will modulate the cooling output as required to maintain the cur rent discharge air cooling setpoint To do this it uses four Step and Wait parameters that are dedicated to chilled water cooling temiperature control 1 discharge air cooling dead band 2 discharge air cooling mod limit 3 discharge air cool
145. y ID Parameter Men Hem Name Dead Band 1 F Supply air Cooling Dead 13 Clg Control Setpoint 55 F Supply air Cooling Setpoint band If heating is enabled menu 8 and there is no heating load the controller will activate the units modulating heating equipment as required to prevent the discharge air temper ature from becoming too cool If it falls below the current dis charge air cooling setpoint by more than the discharge air cooling dead band the operating state will change from Fan On to Fan On Heating Because there is no actual overall heating load the VAV Heat output K6 will remain closed auto during Fan On Heating The closed VAV Heat output can be used to signal heat cool VAV boxes that the unit is supplying coo air Except for the discharge air setpoint used Fan On Heating temperature control is identical to that described above for the heating states Fan On Heating is very useful for applications that require larger amounts of minimum outside air to accommo date for example indoor air quality requirements For a unit with SAT cooling control heat is controlled to maintain the discharge air temperature at the current SAT cooling set point if the user has selected fan on heating yes If the out door air temperature s very cold the mixed air temperature could become unacceptably cold in these units Because the economizer dampers maintain their minimum position during Fan On Heati
146. y Temp alarm will occur As a result the unit will be shut down It will remain shut down until the Low Supply Temp alarm is manually cleared On mixed air or 10096 return air units this alarm will be prevented from occurring until after the recirculate timer expires menu 20 On 100 outdoor air units this alarm will be prevented from occurring until after the low supply temperature alarm delay timer expires menu 20 Fan Failure The Fan Failure Alarm will occur on units if any of the follow are true Building Static Pressure Control Airflow switch is open and supply fan has been turned on for longer than two min utes Duct Static Pressure Control Airflow switch is open and the duct static pressure is less than half of the duct static ressure setpoint and supply fan has been turned on for longer than two minutes Dual Fan Motor 1 low speed motor problem and high speed motor problem have both occurred and not been manually cleared or 2 the high speed motor problem is active and high speed operation is required due to low speed fan motor amps If the Fan Fail alarm occurs the unit will be immediately shut down lt will remain shut down until the Fan Fail alarm is manually cleared The setting on pressure switch PC7 can be adjusted To determine the location of PC7 refer to the Control Locations section of applicable model specific installation manual see Table 1 OA Damper Stuck Economizer po
147. y a knowledgeable service technician to facilitate testing the unit Prolonged operation in this mode could damage the unit Scheduling The self contained unit with the control mode set to auto can be scheduled for daily and holiday operation by using any one of the following four methods 1 Unit controller internal scheduling 2 Network Master Panel NMP scheduling 3 Remote Monitoring and Control RMC Panel scheduling 4 External time clock The following sections describe how to use the unit con troller s internal scheduling features Internal parameters that must be set to use any of the other three scheduling methods are also discussed For information on how to use the NMP and RMC Panel scheduling functions refer to the literature provided with these panels Setting Time and Date Programmable Parameters Keypad Display ID Parameter Name Current Date The MicroTech controller uses the date and time to execute its internal scheduling functions Once set the battery backed internal time clock will keep the current time regard less of whether power is being supplied to the unit You can set the time of day by entering the hour 0 23 minute 0 59 and second 0 59 into the Current Date parameter s three fields You can set the date by entering the day Sun Sat month 1 12 date 1 31 and year 0 99 into the Current Date parameter s four fields hr mn sc day mm dd yy 24 Set Time Date D
148. ys you can minimize scrolling between menus with the keys in the Menu group see below Refer to Figure 2 Status Key Any time the status key is pressed the first menu in the Status category is displayed This is menu 1 Unit Status OM 123 Page 5 Control Key Any time the control key is pressed the first menu in the Control category is displayed This is menu 11 Control Mode Alarms Key Any time the alarms key s pressed the first menu in the Alarm category is displayed This is menu 26 Curr Alarm Switch Key The switch key toggles the display between associated Status and Control category menu items It allows you to quickly check a controlled condition tempera ture pressure position against its setpoint For example by pressing switch when the duct static pressure is currently being displayed Duct item under menu 5 the duct stat ic pressure setpoint will be displayed Duct Spt item under menu 17 If switch is pressed again the actual pressure will be displayed again Note that the switch key will not work with every menu item Tables 3 and 4 list the switch key des tinations for all applicable menu items Menu Group The keys in the Menu group allow you to choose the menu you want to display Refer to Figure 2 Prev Key When the Menu prev key is pressed the dis play will scroll to the previous menu in the structure This action will occur regardless of the current menu numb

VAV or CAV-DTC Control

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