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1. Ht Rate 0 1 00 Min Heat OAT 0 155 Ht Factor 0 255 Min CI Rate 0 1 00 Min Cool OAT 0 155 F Cl Factor OM 109 Page 15 Table 4 Control menus for programs ART5 and ART7 cont d Name Default Shown Switch Key Destination Item Name Service Mode Normal Normal Shutdown Timers Normal Normal Fast Space Sensor Yes No Yes OAT Local Local NMP Remote OPM Remote Alarm Out Blink Off Port A Baud 1200 2400 9600 19200 Notes 1 The default Control Temperature source is Return for program ARTS It is space for program ART7 2 The return air temperature sensor can be selected as the Control Temperature source only on units with program ARTS 3 The supply air temperature set point cooling or heating is not adjustable It is automatically set by the Change function 4 This Step and Wait parameter applies only to units with chilled water cooling It has no effect on units with DX cooling 5 This item is applicable to units with program ART5 only 6 This item is applicable only to units with the direct building static pressure control option Alarm menus Table 5 lists all possible menus and items in the Alarm category The table s range column lists all possible values for each item Following are brief descriptions of the Alarm category menus Current alarm Menu 29 Curr Alarm displays the current alarm
2. 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 Alarm Monitoring About alarms The Applied Rooftop Unit Controller is programmed to monitor the unit for specific alarm conditions that may occur If an alarm condition exists the controller will indicate it 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 Alarm indication Under normal non alarm conditions the amber status LED on MCB1 will be continually lit and the alarm output OBAO will be closed The alarm output s LED indicates the state of the output On indicates OBAO is closed and off indicates OBAO is open Typically the alarm output would be connected to some type of field supplied annunciator If an alarm occurs the amber status LED will flash and the alarm output s state will cycle indicating an alarm condition This indication can also be set to Off so the indicator light will go out if an alarm occurs see Service Menu 28 to change setting Note that the dirty filter alarms have a unique alarm indication Instead of flashing on and off in equal
3. 23 Timers Max MWUP 90 Min Maximum Morning Warm up Time On mixed air units program ART5 morning warm up operation occurs just after the transition from unoccupied to occupied when the Control Temperature is less than the zone heating set point If this is the case the unit controller 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 during Morning Warm up The unit will remain in the Morning Warm up state until either the Control Temperature equals the zone heating set point 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 set point by more than the zone heating deadband when this occurs the controller will enter the Heating state Fan Only state if unit is cooling only The maximum morning warm up time parameter is provided 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 OM 109 Page 43 Page 44 OM 109
4. Discharge air low limit control Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME Menu Item 14 Htg Control Fan On Heating Set Point Deadband 1 F Discharge Heating Deadband If heating is enabled menu 8 and there is no zone load Fan Only state 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 fan on heating set point by more than the discharge heating deadband the operating state will change from Fan Only to Fan On Heating 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 temperature parameters instead of the zone temperature parameters If the supply air temperature rises above the fan on heating set point by more than the discharge heating deadband when at stage 0 the controller will leave the Fan On Heating state and return to Fan Only Fan On Heating is 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 temperature 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 essential for 1
5. 17 High ambient heating lockout csseseseseeseseeeeeseeees 43 Unit status AM an a nai inr kana 18 Morning warm up control aaa 43 Cooling status SA D an NA Aa adik 18 Discharge air low limit control a 44 Heatine stais sesanga n AAA Ben ea NA Ai 19 BARAN a a na Na ena eee enn da Auto Manual Operation ea 20 Temperature control an 44 Gomitrol m6de 3 004 nn ADAKAN ANA GSA Sai 20 High ambient heating lockout a 47 Service AAA a a e a 21 Morning warm up control a 47 Tenant override aaa 21 Discharge air low limit control 47 Operat r override ni dn Sian ciao alan tain 22 i Setting occupied zone temperature setpoints 22 Beura Tan ANOA A ARTS Only ainei re Fast timers i anena Seba A A 23 SERS DES yt EETA a enae ani Scheduling senenin ire BA An an inate ales 23 Unoccupied Control an 48 Setting date and time aaa 23 Heating night Setback nn ann ndak 48 Daily scheduling DA Aa aan a n 24 Cooling night setup ea 49 Holidaysehedulin gn A SANA AAA baie 24 Purge program ART5 only a 49 Alarm Monitoring A4 Dn a KA an aan 25 Optimal Statte Sen RAKAN KAK ak 50 Aboi darmi A E Rta de S 2 Alarm Control nn nn dati catecl aad Ai 51 Displaying alatins iv nn Aa an an SAGA 26 Fault 51 EE bent aes eee 26 ast E TEE A gt
6. 4 This alarm is possible only on units with gas heat Operators Guide The following Operator s Guide sections provide information on the day to day operation of the Applied Rooftop Unit Controller Topics covered are such common tasks as scheduling displaying and clearing alarms and setting the controller for manual operation Any programmable parameters that can affect the controller operation being described are listed at the beginning of each applicable sub section The default keypad programmable values are shown in italics For detailed information on the control processes and their programmable set points and parameters see the Description of Operation and MicroTech DDC Features portions of this manual Determining Unit Status The MicroTech Applied Rooftop Unit Controller provides a variety of information that can be used to determine the overall status of the unit At the Keypad Display most of this information can be found under menus 1 through 10 The following are available Unit status Cooling status Heating status Temperatures Pressures Supply fan status Return fan status program ART5 only Airflow status Outdoor air damper position Outdoor air suitability for free cooling program ART5 only Fan operation Fan cooling heating operating hours OM 109 Page 17 Page 18 OM 109 The first three items are very useful because they summarize the unit s status Using them it can be quic
7. 55 F Low Ambient Cooling PARAMETER NAME Lockout Set Point OAT Diff 3 F Low Ambient Cooling Lockout Differential Mechanical cooling will be disabled whenever the outdoor air temperature is less than or equal to the low ambient cooling lockout set point When this occurs the cooling status state will be either Economizer Only or Temperature Enthalpy Disable if all cooling is not disabled for some other reason When the outdoor air temperature rises above the low ambient cooling lockout set point by more than the low ambient cooling lockout differential mechanical cooling will be enabled again Caution Unless the RPS RDT or RFS RCS unit is equipped with the SpeedTrol low ambient condenser fan control option the low ambient cooling lockout set point should never be set below 45 F Compressor lead lag Programmable parameters KEYPAD DISPLAY ID Menu Item PARAMETER NAME 16 Compressors Lead Circ 1 Lead Cooling Circuit On units with condensing sections the lead and lag refrigeration circuit can be designated either automatically or manually When automatic lead lag operation is selected the lead refrigeration circuit will alternate every time cooling is staged down until all compressors are off If automatic lead lag is not desired it can be manually designated which circuit will be lead That circuit will remain lead until the lead lag designation is manually changed again When refrigeration
8. 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 Setting occupied zone temperature setpoints Programmable parameters KEYPAD DISPLAY ID Menu Item 12 Heat Cool Setpoints Keypad Zone Setpoint Adjust PARAMETER NAME Location Cooling Spt 75 F Zone Cooling Setpoint Heating Spt 70 F Zone Heating Setpoint During occupied periods the MicroTech CAV ZTC controller will control the unit s cooling and heating equipment to keep the zone temperature between the zone cooling set point and zone heating set point There are two mehtods of setting these set points 1 they can be adjusted at the zone sensor or 2 they can be adjusted at the keypad or PC Note that either method can be used regardless of whether the unit is set up for space or return air temperature control Setpoint adjustment from a zone sensor If the zone temperature sensor package equipped with the optional remote set point adjustment feature is connected to the controller the occupied zone cooling and heating set points can be adjusted at the zone sensor To enable this feature set the zone set point adjust location parameter to T Stat The controller will then obtain its zone set points from the two set point adjustment potentiometers on the zone sensor When T Stat is selected the current set points will be displayed at the
9. Setpoints Cooling Spt Heating Spt Clg Deadband Htg Deadband Clg PA Htg PA Mod Limit Wait Time Max Step 13 Clg Control Set Point Min OAT OAT Diff Min Spt Max Spt Stg Timer Deadband Mod Limit Wait Time Max Step PA Time 0 60 Min 0 60 F 0 60 Min 1 100 40 100 F 2 Temperatures Supply Air 0 100 F 2 Temperatures Outdr Air 1 9 F 40 100 F 40 100 F 5 60 Min 0 10 F 1 60 F 1 60 Sec 1 60 Sec 0 255 Sec 40 140 F 2 Temperatures Supply Air 40 100 F 0 100 F 2 Temperatures Outdr Air 40 140 F 40 140 F 0 60 Min 0 60 Min 0 10 F 1 60 F 1 60 Sec 1 60 Sec 0 255 Sec 90 250 F 2 Temperatures Supply Air 20 50 F 2 Temperatures Supply Air 90 150 F 2 Temperatures Return Air Occ Cool Only Occ Heat Only Htg Control Set Point Fan On Htg Occ Fan Only Calibrate Return 2 Temperatures Cntl Temp Max OAT Min Spt Max Spt Space Netwrk T Stat Stg Tmr 1 Stg Tmr 2 Deadband Keypad 55 99 F 2 Temperatures Cntl Temp Mod Limit Wait Time 40 99 F 2 Temperatures Cntl Temp Max Step 0 10 F PA Time 0 10 F Alarm Limits Hi Supply Lo Supply Hi Return 0 60 Min Compressors Lead Circ OM 109 Page 13 Table 4 Control menus for programs ART5 a
10. category menus Control mode Menu 11 Control Mode allows the unit to be set for automatic or manual operation For more information see the Auto Manual Operation section in the Operator s Guide portion of this manual Heat cool changeover Menu 12 Ht Cl Chgovr contains temperature parameters that are used to determine whether the unit will be allowed to supply heating cooling or neither 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 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 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 OM 109 Page 11 Page 12 OM 109 Compressor lead lag On some RoofPak systems that have compressorized cooling menu 16 Compressors can be used to designate the lead and lag compressors An automatic lead lag selection is available On units that have a s
11. fan output is closed On units equipped with modulating chilled water the unit status display shows Unoccupied Cooling during the Unoccupied Cooling state On units equipped with compressors the unit status display shows 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 section Unoccupied heating When heating is required to satisfy the night setback setpoint during unoccupied periods the unit starts and enters the Unoccupied Heating state During Unoccupied Heating a mixed air unit s outside air dampers are closed a 100 outside air or 30 unit s dampers are driven to 100 open and the fan output is closed On units equipped with modulating steam or hot water the unit status display shows Unoccupied Heating during the Unoccupied Heating state On units equipped with gas or electric heat the unit status display shows Unoccupied Heating Stage during the Unoccupied Heating state The wildcard character indicates the numbert of active heating stages For more information see the Unoccupied Control section 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 transition that can occur as a result of normal temperature and pressure con
12. one half second intervals the amber status LED and the alarm output LED will flash on for 9 10 second and off for 1 10 second when either dirty filter alarm occurs If the optional Remote Status Panel is connected to the unit the following alarms can also be indicated by a lit light on the panel Freeze Shutdown Freeze light lit Smoke Shutdown Smoke light lit Freeze Problem Freeze light lit Heat Fail Heat light lit Cooling 2 Fail Cool light lit Cooling 1 Fail Cool light lit Ist Filter Dirty Filter light lit Fnl Filter Dirty Filter light lit Note The controller s dirty filter alarms are caused by a pressure drop sensed by SPS5 or SPS6 exceeding a programmable limit menu 22 However the Filter light on the panel is lit by a pressure switch PC5 or PC6 contact closure Therefore the dirty filter alarm indications on the controller and the panel will probably not occur simultaneously It is recommended that the programmable limits and the pressure switch settings be set so that they match for both the first and final filters Priority The various alarms that can occur are prioritized according to their severity Three categories are possible faults problems and warnings Regardless of the alarm type a message that identifies the alarm will be generated for display at the keypad display or PC Table 6 summarizes the alarms that can occur in CAV ZTC units Faults are the highest priority alarms If a fault o
13. 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 heating operation The cooling status or heating status can be displayed by selecting menu 7 cooling or menu 8 heating 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 section as applicable Mutliple unit applications Common zone temperature control for multiple unit applications is available with the optional Remote Monitoring and Control RMC Panel To use this control strategy Network is selected as the Control Temperature source at each unit controller in the group In addition each unit controller s zone cooling and heating set points and deadbands are set so that they match the others in the group For more information see Bulletin No OM 121 MicroTech Applied Rooftop Unit Remote Monitoring and Control Panel Economizer program ART5 only KEYPAD DISPLAY ID PARAMETER NAME Menu Item 12 Heat Cool Cooling Spt 75 F Zone Cooling Set Point Clg Deadband 1 F Zone Cooling Deadband Clg PA 12 Min Cooling PA Time Mod Limit 10 F DA Set point Mod Limit Wait Ti
14. Note that the same result could have been accomplished by pressing the CLEAR key instead of the ENTER key Keypad Display Menu Reference The following tables show every menu item and field in the menu structure of CAV ZTC programs ART5 and ART7 These menus and items can all be displayed with the keypad display Monitor software provides many additional monitoring features and adjustable parameters Status menus Table 3 lists all possible menus and items in the Status category The table s range column lists all possible values for each item Following are brief descriptions of the Status category menus Unit status Menu 1 Unit Status indicates 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 temperature at the selected representative zone sensor Note On 100 outdoor air units program ART7 the mixed air temperature is actually the preheat temperature Pressures Menu 3 Pressures provides the current pressures at all connected sensor locations Fans airflow status Menu 4 Fans Airflow indicates which fans are currently on and whether there is airflow through the unit Airflow s
15. Start up Initialization Fan Only Vv Fan On Heating A Open a coom aa O Unoccupied cooing V Unoccupied Heating No Yes Yes 1 The outside air damper will close 3 minutes after the unit enters the Off state 2 This fan output will open 3 minutes after the unit enters the Off state 3 On units with gas heat the furnace may enter a pre heat mode during Start up Initialization if a need for heat is detected 4 This state is not applicable to cooling only units T Heating D Notes Displaying the operating state If the unit is not in a special service state the current unit status menu 1 shown is the current operating state At the keypad the current unit status can be displayed simply by pressing the Status key For more information see the Determining Unit Status section in the Operators Guide portion of this manual Operating state descriptions Off In the Off operating state the unit is shut down The fans are off the outside air dampers are closed the return inlet vanes if any are open VFDs at 0 and cooling and heating are disabled The fan output is open When the Off state is displayed the reason the unit is in Off is also displayed Six different Off states are possible Off Alarm Off Service Off Manual Off Network Off Unoccupied Off Fan Switch ni MI NN Start requested The Start Requested state is a transitional operating state It will be momentarily d
16. When the controller indicates that an alarm condition has occurred the alarm with date and time of occurance are displayed under the current alarm menu 29 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 Previous alarm When the current alarm is cleared or replaced by a higher priority alarm it is stored in the previous alarm buffer menu 30 The previous alarm buffer stores the past eight alarms including the time and date of occurance 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 automatically or manually See Table 6 for listing of possible alarms An auto reset alarm will immediately clear whenever the alarm conditions that caused it disappear A manual reset alarm can be cleared at the keypad display optional RMC Remote Status Panel or PC gt To clear an alarm from the unit s keypad Press the CLEAR key while the current alarm is in the display Page 26 OM 109 gt To clear an alarm from the Remote Status Panel Turn the fan switch to off and then back to on after a brief pause gt To clear an alarm from the RMC Panel s keypad 1 Change the keypad controller interface to the affected unit 2 Press the CLEAR key while the current
17. about to start The duration of the Start up Initialization state is defined by the start up initialization timer s setting Its default value is three minutes PC adjustable only Caution The start up initialization timer 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 output to prepare for fan operation Mixed air or 100 return air units program ART5 only On mixed air units equipped with the direct building static pressure control option program ART5 the return fan inlet vanes maintain their full open position fixed during Start up Initialization This will assure that the supply and return fans are evenly loaded when fan start up occurs 100 outdoor air units program ART7 only On 100 outdoor air units the outside air dampers are fully opened during Start up Initialization If the dampers do not open to at least 50 the OA Damper Stuck alarm will occur and the supply fan will not be allowed to start If the unit is equipped with a high turndown gas furnace and heating is required the furnace will enter a special burner start up sequence upon entering Start up Initialization At the beginning of Start Up Initialization the burner 90 second pre purge cycle is started simultaneously with a four minute timer When pre purge is complete the burner will be turned on and be held at its low fire position for the remainder of the four minute t
18. air is cool low enthalpy but unable to satisfy the cooling load Normally this will happen when 1 the outside air damper is more than 95 open and 2 the supply air temperature is above the discharge cooling set point by than the discharge cooling deadband value The transition can also occur if 1 the economizer has been active for at least 10 minutes and 2 the supply air temperature is above the discharge cooling set point by an amount greater than or equal to the economizer deadband value plus 3 F This backup feature will ensure that cooling is provided if the economizer dampers get stuck If the outdoor air enthalpy is low when mechanical cooling is activated Cooling or Unoccupied Cooling state the outside air dampers will be driven to full open They will remain there until either mechanical cooling is no longer necessary or the outdoor air is no longer suitable for free cooling If mechanical cooling is no longer necessary the economizer dampers will resume modulation During occupied operation the outside air dampers will be driven to the current 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 mechanical cooling operation see the Cooling Multstage or Cooling Modulating section as applicable Changeover method Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME Menu Item 21
19. 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 Previous alarm Menu 30 Prev Alarm displays what the eight previous alarms were and when they 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 Page 16 OM 109 Table 5 Alarm menus for programs ART5 and ART7 Name Switch Key Destination Default Shown i i Curr Alarm No Active Alarms Freeze Shutdown Smoke Shutdown Zone Sensor Fail Ret Sensor Fail Sup Sensor Fail High Return Temp High Supply Temp Low Supply Temp Fan Fail Freeze Problem OAT Sensor Prob Zone Sensor Prob Ret Sensor Prob Mixd Sensor Prob V Heat Fail Cooling 2 Fail Cooling 1 Fail OA Damper Stuck Air Flow Warning 1st Filter Dirty Fnl Filter Dirty Misc Temp 2 Fail Misc Temp 1 Fail No Active Alarms 29 30 Prev Alarm No Active Alarms Same as Curr Alarm hr mn mm dd yy Notes 1 This alarm is possible only on units with program ART7 2 This alarm is possible only on units with program ART5 3 This alarm is possible only on units with gas or electric heat
20. case some of the information in this manual may not be applicable For brevity a program tag has been assigned to each standard program number The program tag will be used throughout this manual to identify and classify the two types of CAV ZTC rooftop units For example if a table pertains to ART5 units it is referring to units with a mixed air or 100 return air intake If it pertains to ART7 units it is referring to 100 outdoor air units Note The leading 9 of the software part number is not printed on the software ID tag Table 2 Program identification PROGRAM ID SOFTWARE PART NO ROOFTOP UNIT DESCRIPTION ARTS 950163 CAV Zone Temperature Control ZTC Mixed Air or 100 Return Air ART po 950166 CAV Zone Temperature Control ZTC 100 Outdoor Air Getting Started The MicroTech Applied Rooftop Unit Controller is a self contained device that is capable of complete stand alone operation It can also be included in a network with other unit and auxiliary controllers Regardless of whether the controller is stand alone or part of a network information in the controller can be displayed and modified by using any of the following three methods Using the keypad display in the unit s main control panel Using the keypad display in an optional Remote Monitoring and Control RMC panel Using an optional PC equipped with monitor software The following Getting Started sections describe how to
21. cooling and heating set points Whe the Control Temperature is above the zone cooling set point by more than the zone cooling deadband the cooling equpiment is activiated and the operating state changes to a cooling state Economizer Cooling Unoccupied Economizer or Unoccupied Cooling When the Control Temperature is below the zone heating set point by more than the zone heating deadband the factory installed heating equipment if any is activated and the operating state changes to 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 or heating load is satisfied For more information see the following sections that apply to units with various types of cooling and heating equipment Note that cooling and heating can never occur simultaneously because the controller will prevent the zone set points and deadbands from being set so that there is overlap of the deadband ranges In doing this the controller will always give the zone cooling set point the highest priority Regardless of whether the cooling set point is lowered the heating set point is raised or either deadband is increased the controller will automatically lower the zone heating set point enough to prevent the deadband ranges from overlapping Note The above description assumes that cooling and heating control is enabled If cooling or heating control is disabled
22. heat to the space The outside air dampers remain closed in Unoccupied Heating states on mixed air units They are driven fully open on 100 or 30 outside air units When the zone temperature rises above the night setback set point 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 PC adjustable only After the unit is started heating equipment control during night setback heating operation is similar to that during occupied operation Since the Control Temperature is likely well below the zone heating set point menu 12 heating control is activated and the heating output is rapidly increased When night setback operation ends the heating equipment is immediately shut down regardless of the interstage timing For more information see the Heating Multistage or Heating Modulating section as applicable Emergency occupied mode program ART5 only If the zone temperature sensor fails during the Off Unoccupied state when the outdoor air temperature is below 40 F and the night setback set point is set above 40 F and heating is enabled the unit will start and operate in an emergency occupied mode During this mode the controller will operate just like it does during occupied periods However if the space sensor had been selected as the Control Temperature source the controller will automatically change it to
23. keypad or PC but the controller will not allow them to be changed at the keypad For more information see the Analog Inputs section in the Field Wiring portion of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller Setpoint adjustment from the keypad or PC To adjust the zone cooling and heating set points from the keypad or PC set the zone set point adjust location parameter to Keypad this is the default setting The controller will then ignore its two analog inputs A9 and A10 that can be used for remote set point adjustment The Keypad setting must be selected if 1 a zone sensor is not connected or 2 a zone sensor is connected but it does not include the set point adjustment potentiometers Note that when the zone sensor package that includes the optional remote set point adjustment pots is connected to the controller Keypad can be selected to disallow remote set point adjustment Fast timers Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME Menu Item Operation Timing Flag If desired the controller s internal timers can be temporarily sped up by using the operation timing flag When set to Fast the operation timing flag will reset the following timers to 20 seconds Start up initialization timer Recirculate timer program ART5 only Low supply temperature alarm delay timer program ART7 only Cooling interstage timer Heating interstage timer These timers will
24. max step which must be less than or equal to the wait time 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 set point 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 set point by more than the mod limit see below Mod limit The mod limit sets the gain the responsiveness of the control loop to a given variable s deviation from set point The actual amount of time an actuator is driven either open or closed step period during each wait time period is set in proportion to this deviation The following equation can be used to determine the step period if the controlled variable s deviation from set point is less than or equal to the mod limit and greater than the deadband Max Step Step Period Deviation from Set Point x _ tep Perio eviation from Set Point l T Timir For example assume that the discharg
25. mode The Manual Off control mode selection 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 Manual Off control mode selection can be overridden 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 If there is no RMC Panel connected this risk can also be eliminated by placing the unit into the Shutdown service mode see below Auto The Auto control mode selection allows the unit to operate automatically This means that the unit will start and stop according to any scheduling tenant override operator override or unoccupied temperature control commands Once running the unit will act as required to maintain its temperature and pressure control set points NOTE This setting is required if the unit is to be started and stopped through a network or Open Protocol command If desired the external on off and heat auto cool switches on the Remote Status Panel can override the Auto mode and either shut down the fans or disable heating or cooling Occupied The Occupied control mode selection causes the unit to run continuously in the occupied mode Any scheduling commands are prevented from shutting down the unit Both heating and cooling are allowed to operate as
26. necessary to maintain the temperature control set points Occ Cool only The Occ Cool Only control mode selection causes the unit to run continuously 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 set points Heating is disabled Occ Heat only The Occ Heat Only control mode selection causes the unit to run continuously 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 set points Cooling is disabled Occ Fan only The Occ Fan Only control mode selection causes the unit to run continuously 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 is a special service mode When selected the Calibrate mode automatically calibrates the position feedback pot on the outdoor air damper actuator Following is a description of the Calibrate procedure After Calibrate is activated the fans are shut down and the outdoor air dampers are driven open When three minutes have elapsed the controller records the feedback value of the actuator as equivalent to the fully open position The feedback voltage should be approximately 0 VDC for the outdoor air damper actuator The controller then drives the actuator clo
27. 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 2 Temperatures i 2 Supply Air 65 F Item Line upply Air 65 ii Password protection The MicroTech controller includes password protection to guard against the entry of inadvertent changes When an attempt is made to change the value of an adjustable parameter with the keypad the controller prompts the user to enter the password If the correct password is entered the controller allows changes to be made 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 keystroke sequence ENTER ENTER ENTER ENTER This password is not adjustable See Keypad Functions below for more information Keypad functions The MicroTech controllers 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 1 Unit Status Economizer CATEGORY MENU ITEM ACTION STATUS ALARMS t t CLEAR PREV PREV INCR NEXT NEXT DECR CONTROL SWITCH 4 4 ENTER Category group Acting like book
28. operation begins If the scheduled occupied start up time occurs during purge operation the unit will continue running without interruption Optimal Start Programmable parameter KEYPAD DISPLAY ID PARAMETER NAME Menu Item 27 Optimal Start Opt Start Off Auto Update Yes Ht Rate 0 400 F M Heat OAT 35 Ht Factor 25 Min Cl Rate 0 400 F M Cool OAT 85 F Cl Factor 25 Min When Optimal Start is turned on the number of minutes until start up is calculated before each scheduled start The software uses the start history outdoor air temperature and space temperature to determine when the unit should start It may start up to four hours before the scheduled start time If the control temperature is below the heating set point by more than the dead band Optimal Start will be based on the Heating parameters found in keypad menu 23 If the control temperature exceeds the cooling set point by more than the dead band Optimal start will be based on the Cooling parameters Start up 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 following formula Calculated Heating Rate Ht Rate OAT Heat OAT Heat Factor The minutes to occupancy are calculated by dividing the difference between the heating set point and the space temperature by the Calculated Heating Rat
29. output device is a hot water valve actuator Output relay OBA5 drives the valve open when energized and OBA4 drives the valve closed when energized Refer to Figure 9 Note that Figure 9 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 ti the discharge air temperature is below the set point by more than the deadband Since the deviation from set point is approximately 60 of the mod limit the step period for this cycle ts is set equal to 60 of the max step tm During the step period output OBAS is energized and thus the hot water valve is driven open As a result the discharge air temperature rises At the beginning of the second wait time cycle time tz the discharge air temperature is within the deadband range and therefore the step period for this cycle ts is set equal to zero Since the step period is zero neither OBA4 nor OBAS 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 ts the discharge air temperature is above the set point by more than the mod limit Since the deviation from set point is greater than the mod limit the step period for this cycle tss is set equal to the wait time During the step period output OBA4 is energized and t
30. return to their normal settings 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 by a knowledgeable service technician to facilitate testing the unit Scheduling The rooftop unit 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 controller 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 For information on how to connect an external time clock refer to the Field Wiring portion of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller Scheduling method interaction When any of the above scheduling functions is calling for occupied operation the unit will operate if its control mode is Auto and it is not locally or remotely disabled see below Conversely a unit will enter its unoccupied mode only when all of the above scheduling methods are c
31. stage 2 operation the modulating gas valve modulates as required to maintain the discharge heating set point During stage 0 operation the furnace is shut down but the controller remains in the heating state Except during unit shutdown a stage change generally can only occur 1 after a heating interstage timer has expired and 2 if the discharge temperature is above or below the discharge heating set point by more than the discharge heating deadband After any stage change occurs the heating interstage timers start timing The transitions from stage 1 to stage 2 stage 2 to stage 1 and from stage 0 to Fan Only are all governed by Stg Tmr 1 The transition from stage 1 to stage 0 is governed by Stg Tmr 2 There is no stage timer from stage 0 to stage 1 There is one additional constraint that applies to the stage down transition from stage 2 to stage 1 The modulating gas valve must be fully closed before the stage down can occur To determine whether the valve is closed the controller compares the stroking open time with the stroking closed time There is one exception to the above staging constraints If the supply air temperature drops below the minimum discharge heating set point by more than the discharge heating deadband during stage 0 operation the stage up transition to stage 1 will occur regardless of the interstage timer or Control Temperature When heating is operational Morning Warm up Heating or Un
32. state After the interstage timer expires another stage down would cause the controller to leave the cooling state If contradictory stage change conditions exist when the cooling interstage timer expires the controller will always stage down cooling For example if the discharge air temperature is below the minimum discharge cooling set point stage down condition when the Control Temperature is above the zone cooling setpoint by more than the zone cooling deadband stage up condition a stage down will occur Project ahead The Project Ahead algorithm works to prevent the Control Temperature from overshooting the zone cooling set point during periods in which the space temperature is changing while it is far from the set point for example just after start up Using the cooling PA time parameter the controller anticipates what the Control Temperatures will be if it continues to change at its current rate The controller uses this anticipated Control Temperature as the input to its cooling control processes The result is that the cooling output is increased or decreased early enough to avoid Control Temperature overshoot For most applications the default cooling 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 Low ambient cooling lockout Programmable parameters KEYPAD DISPLAY ID Menu Item 13 Clg Control Min OAT
33. the Step and Wait function rapidly increases the cooling or heating output This feature assures that the Control Temperature will approach its set point as quickly as possible during transient period for example after unit start up The mod limit parameter s units are in temperature Note The discharge set point change is calculated in tenths of degrees The controller keeps a running total of the discharge set point as adjustments are added or subtracted This running total which is used in the temperature control processes is also in tenths of degrees Any fractional part of the current set point is truncated for display only Deadband The deadband sets a range in which no control action will be taken If the Control Temperature is within the deadband range the discharge cooling or heating set point will not change Note that the deadband parameters value is added to and subtracted from the zone set point to determine the deadband range For example if the zone cooling deadband is 1 F and the zone cooling set point is 75 F the discharge cooling set point will not be changed when the Control Temperature is 74 F 75 F or 76 F The deadband parameter s units are in temperature Adjusting change parameters Appropriate default Change parameter values are loaded into each controller at the factory see Table 4 These default values will provide proper zone temperature control for most applications therefore field tuning is usually n
34. 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 Nontimed tenant override A simple SPST switch can be used to override unoccupied operation When this switch is closed the unit will start and run in the occupied mode When this switch is open the unit will be controlled by any active scheduling function internal network or external time clock If there is no active scheduling function the unit will remain in the unoccupied mode OM 109 Page 21 Page 22 OM 109 Operator override Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME Menu Item 25 Schedule Override 0 00 Hr From the keypad or PC the same override timer that is automatically set by the tenant override switch and override increment parameter see Tenant Override above can be manually set 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 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
35. the return air sensor If the outdoor air temperature rises above 40 F or if the Zone Sensor Prob alarm clears the emergency occupied mode will end If desired the emergency occupied mode can be disabled by setting the night setback set point to 40 F Cooling night setup Programmable parameters KEYPAD DISPLAY ID Menu Item PARAMETER NAME 17 Unocc Htg Clg Cooling Spt 85 F Night Setup Set Point Po Night Setup Differential If a zone temperature sensor ZNT1 is connected to the controller night setup cooling control is available Following is a description of operation If the zone temperature rises to the night setup set point when the unit is in the Off Unoccupied state the unit will start up and run If the unit has an economizer and the outdoor air enthalpy is low the controller will enter the Unoccupied Economizer state after start up Note that there is no minimum outside air damper position control during the Unoccupied Economizer state If outdoor air is either not available or not cool enough to maintain the current discharge cooling set point the controller will activate mechanical cooling as it enters the Unoccupied Cooling state If the outdoor air enthalpy is low the economizer s outside air dampers will be wide open during Unoccupied Cooling If the outdoor air enthalpy is high the outside air dampers will be fully closed during Unoccupied Cooling If the unit is 100 or 30 outside air the dampers are dr
36. two position coil valve and modulates the face and bypass dampers as required to maintain the current discharge heating set point To do this it uses four Step and Wait parameters that are dedicated to heating temperature control 1 discharge heating deadband 2 discharge heating mod limit 3 discharge heating wait time and 4 discharge 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 portion of this manual If the Step and Wait function fully closes the face damper during occupied periods the controller will leave the Heating state and enter Fan Only This can only happen if the Control Temperature is greater than the zone heating set point by more than the zone heating deadband To determine whether the face damper is closed the controller compares the stroking open time with the stroking closed time Note The heating interstage timer is ignored when modulating steam or hot water heat is used Project ahead The Project Ahead algorithm works to prevent the Control Temperature from overshooting the zone heating set point during periods in which the space temperature is changing Using the heating PA time parameter the controller anticipates what the Control Temperatures will be if it continues to change at its current rate The controller uses this anticipated Control Te
37. 00 outdoor air applications in cold climates Heating Modulating Temperature control Programmable parameters KEYPAD DISPLAYID Men item 12 Heat Cool Heating Spt 70 F Zone Heating Set Point Htg PA 8 Min Heating PA Time Mod Limit 10 F DA Set Point Mod Limit Wait Time 1 Min DA Set Point Wait Time Max Step 10 DA Set Point Max Step 14 Htg Control Set Point ___ F _ Discharge Heating Set Point Min Spt 60 Minimum Discharge Heating Set Point Max Spt 120 F Maximum Discharge Heating Set Point Stg Tmr 1 5 Min Heating Interstage Timer Stg Tmr 2 5 Min Heating Stg 1 to Heat Stg 0 Interstage Timer Deadband 1 F Discharge Heating Deadband Mod Limit 60 F Discharge Heating Mod Limit Wait Time 30 Sec Discharge Heating Wait Time Max Step 30 Sec Discharge Heating Max Step 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 set point by more than the zone heating deadband value 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 heating set point based on the deviation of the Control Temperature from the zone heating set po
38. 1 1 1 1 1 1 1 Il 1 1 1 1 1 1 2 3 1 2 3 4 1 1 1 2 3 4 Table 4 Control menus for programs ART5 and ARTZ contd Name Switch Key Destination Default Shown Holiday Date 1 Date Dec 25 N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 5 Days N A J an Dec 0 31 1 Dur 1 Day s 2 Date N A 0 2 Dur 1 Day s 3 Date N A 0 3 Dur 1 Day s 4 Date N A 0 4 Dur 1 Day s 5 Date N A 0 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 10 Date N A 0 10 Dur 1 Day s 11 Date N A 0 11 Dur 1 Day s 12 Date N A 0 12 Dur 1 Day s 13 Date N A 0 13 Dur 1 Day s 14 Date N A 0 14 Dur Optimal Start Opt Start ef e n n NI N N N n ef nj ej l nj ej ej nj H ej nj el ej nj ej el oj Hj ej nj IO Auto Update
39. Calibrate The Manual Disable cooling state can also occur if the controller is in the Shutdown service mode menu 28 All cooling will be disabled during the Manual Disable state Switch disable If the cooling status state is Switch Disable it means that the switches on the Remote Status Panel or other field supplied device have been set to disable cooling All cooling will be disabled during the Switch Disable state Network disable If the cooling status state is Network Disable it means that a network command has disabled all cooling Heating status The heating status state menu 8 indicates whether heating is enabled or disabled If heating is disabled the reason is given Following are descriptions of the various heating status states Heating allowed When the outside air is not warm enough to prevent heating operation the heating status state will be Heating Allowed In this state the unit will supply heat as required to maintain the heating set points Off OAT lockout When the outside air is too warm for heating operation the heating status state 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 state will be Off Unoccupied Off Alarm When the unit or its heating equipment is shut down by an alarm all heating will be disabled and the heating status state will be
40. Off Alarm Manual disable If the heating status state is Manual Disable it usually means that the control mode menu 11 has been set to one of the following Manual Off 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 28 All heating will be disabled during the Manual Disable state Switch disable If the heating status state is Switch Disable it means that the switches on the Remote Status Panel or other field supplied device have been set to disable heating All heating will be disabled during the Switch Disable state Network disable If the heating status state is Network Disable it means that a network command has disabled all heating OM 109 Page 19 Page 20 OM 109 Auto Manual Operation WARNING 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 PARAMETER NAME Menu Item 11 Control Mode Control Mode The unit can be set up for automatic or manual operation by selecting the control mode menu 11 Following are descriptions of the seven possible control mode selections Manual off control
41. Operation Manual OM 109 3 Group Applied Systems Part Number 573437Y Date October 1997 Microlech Applied Rooftop Unit Controller CAV ZTC Control Programs ART5 and ART7 Used with McQuay models RPS RFS RCS RDT RDS amp RAH McQuay 1997 McQuay International Air Conditioning Contents Intr d ctio nn mn nn An a ni a Te A KAN 3 Economizer program ART5 only na 34 eE Temperature control a 34 Software Identification ea 4 Changeover method nan 36 Getting Started a 5 Minimum ventilation air volume control 37 Using The Keypad Display nan 5 0 30 Outside Air Damper ena 37 Menu str cture a Aan ARAK A nan a SA 5 Minimum ventilation air volume control 37 Display fofmat ss Ban ann BAN BA AA Ai 6 eee d protection 6 Goolings Miultistage sen io BA diastase ann a 38 KA a fi itr nce ei ea eee 6 Temperature Contolera eiris 38 D A ans Ne cea Ma 8 Low ambient cooling lockout aaa 39 YP Bana a a Compressor lead lag aaa 39 sop a Men AA an ee Cooling Modulating senses nanei ani 40 E E E nen en A a Temperature controli irte partr aiani 40 re Baas a a A EAN e EET E E A aa 4 Heating Multistage nn naaa in AG ian a ians 42 Operator s Guide man A Aen a AAA AAA 17 aaa Pep ore ag 4 Determining Unit Status wo cece ea
42. Outdr Damper Enthalpy Yes Economizer Changeover Flag Changeover 60 F Economizer Changeover Set Point Chngovr Diff 1 Economizer Changeover Differential 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 DO 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 economizer changeover set point 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 model 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 set point The external enthalpy control input is then ignored To use the d
43. Seine a e ae e A 27 roblems naa WALD Siri An ARA E AA D abai tag 54 Description of Operation ea 28 MicroTech DDC Features a 55 a oS Dn noes Saigin a8 Step And Wait Algorithm esa 55 About operating states sh nn Ban AA Be badi 28 Rice Ge andvat 55 Operating state descriptions aaa 29 SSP f P AEE S Ye gle A a Seene chit 31 Description Of operation ee en 55 querce CALS sssini reiii ises E E AEE A O P E nan a 57 Start Up Control cis me nana in Sani daaa Cai 32 Change Algorithm naaa 57 Belorestartup Bn Sdn a nn as 32 About change D a A a ah a a a a 57 Fan start up mixed air or 100 return air units Description Of opera oms Ann Aita 58 progam ARTS inn Sandi a ie 32 Adjusting change parameters nn 59 Fan start up 100 outdoor air units Project Ahead Algorithii essenin 59 program ART 33 About project ahead aan 59 Description of operation ea 59 Head Cool Changeovet kena dana aha akai 33 Adjusting PA time parameters a 60 Temperature Control an Ann a Bentan ai 33 McQuay MicroTech RoofPak and VaneTrol are registered trademarks of McQuay International Page 2 OM 109 Monitor and Open Protocol are trademarks of McQuay International 1997 McQuay International All rights reserved throughout the world Introduction This manual provides information about the Mi
44. adjusted only by trained personnel that have a thorough understanding of how they affect overall system operation There are four Change parameters that regulate the control loop action 1 wait time 2 max step 3 mod limit and 4 deadband Following are descriptions of each parameter Note The same wait time max step and mod limit parameters are used for both cooling and heating control However different deadband parameters are used for cooling and heating control At the keypad all of these parameters can be found under menu 12 Heat Cool Wait time The wait time sets the control loop sampling rate During each wait time cycle the Control Temperature source is read and the discharge cooling or heating set point is adjusted accordingly The wait time parameter s units are in time minutes Max step The max step defines the maximum amount the set point can be raised or lowered at the beginning of each wait time cycle Depending on the deviation of the Control Temperature from set point the actual amount of set point change is some percentage of the max step The greater the deviation is the greater the set point change will be The max step parameter s units are in percent For cooling control the effective max step is the entered percentage of the difference between the minimum and maximum discharge cooling set points menu 13 For heating control the effective max step is the entered percentage of th
45. alarm is in the display Note Some of the safety devices that detect alarm conditions require a manual reset at the device before the controller alarm can clear See Table 6 for listing of possible alarms Setting alarm limits Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME 15 Alarm Limits Hi Supply 170 F High Supply Temperature Limit Lo Supply 40 F Low Supply Temperature Limit Hi Return 120 F High Return Program ART5 Only Temperature Limit Five alarms in Table 6 have adjustable limits that are used to trigger the alarm These are the high and low supply temperature alarms and the high return temperature alarm program ART5 only Although the default settings should be suitable for most applications the alarm limits can be set as necessary with the keypad or a PC The default settings are shown above OM 109 Page 27 Description of Operation The following sections describe how the various CAV ZTC control processes work to maintain temperature and pressure control The Operating States and Sequences section provides an overall description of unit operation The subsequent sections provide detailed descriptions of the various control processes and how their set points and parameters affect them These set points and parameters are listed at the beginning of each applicable sub section The default keypad programmable values are shown in italics Note Not all the features covered in this section apply
46. alling for unoccupied operation This rule can be summarized as Or for On And for Off Therefore any unused schedules should either be set for continuous unoccupied operation or in the case of an RMC or NMP schedule not be assigned to a unit Note This interaction is the opposite of the scheduling method interaction for MicroT ech equipped McQuay chillers These chillers use an And for On Or for Off rule Setting date and time Programmable parameters KEYPAD DISPLAY ID Menu Item PARAMETER NAME 24 Set Date Time mm dd yy Current Date day hr mn sc Current Day Time 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 regardless of whether power is being supplied to the unit The date can be set by entering the month 1 12 date 1 31 and year 0 99 into the current date parameter s three fields The day of the week and the time of day can be set by entering the day Sun Sat hour 0 23 minute 0 59 and second 0 59 into the current day time parameter s four fields OM 109 Page 23 Page 24 OM 109 Daily scheduling Programmable parameters KEYPAD DISPLAY ID Menu Item 25 Schedule Sun 00 00 00 00 Sunday Schedule Mon 00 00 00 00 Monday Schedule Tue 00 00 00 00 Tuesday Schedule Wed 00 00 00 00 Wednesday Schedule PARAMETER NAME Thu 00 00 00 00 Thursda
47. ate but the heating system will be disabled It will remain disabled until the flame safeguard control is manually reset Then when R24 de energizes the Heat Fail alarm will automatically clear The FSG control is located in the gas furnace control box For more information on it refer to the separate installation manual supplied with the gas furnace and the Sequences of Operation portion of the model specific installation manual see Table 1 Cooling 2 fail On units with factory equipped compressorized cooling the Cooling 2 Fail alarm will occur whenever one or both compressors in refrigeration circuit 2 are shut down by a safety device or by switch CS2 The following safeties could cause the Cooling 2 Fail alarm compressor motor protector 2 or 4 MP2 or MP4 high pressure switch 2 or 4 HP2 or HP4 and oil pressure switch 2 or 4 OP2 or OP4 MP4 HP4 and OP4 are applicable to four compressor units only If any of these devices trip relay R6 or R8 will de energize and open a set of contacts connected to the controller thus causing the Cooling 2 Fail alarm If the alarm is caused by a high pressure condition relay R6 will remain de energized until it is manually reset by cycling switch CS2 If the alarm is caused by a low oil pressure condition relay R6 or R8 will remain de energized until OP2 or OP4 is manually reset MP2 and MP4 OM 109 Page 53 Page 54 OM 109 will automatically reset when the compressor motor windings c
48. ate and the supply fan is started the burner will remain at the preheat firing rate for four minutes before normal heat modulation begins Hot water or steam valve control When heating is operational Morning Warm up Heating or Unoccupied Heating state the controller modulated the heating valve as required to maintain the current discharge heating set point To do this it uses four Step and Wait parameters that are dedicated to heating temperature control 1 discharge heating deadband 2 discharge heating mod limit 3 discharge heating wait time and 4 discharge 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 portion of this manual If the Step and Wait function fully closes the heating valve during occupied periods the controller will leave the Heating state and enter Fan Only This can only happen if the Control Temperature is greater than the zone heating set point by more than the zone heating deadband To determine 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 modulating steam or hot water heat is used Hot water or steam damper control When heating is operational Morning Warm up Heating or Unoccupied Heating state the controller opens the
49. ble parameters KEYPAD DISPLAY ID PARAMETER NAME Menu Item 13 Clg Control Min OAT 55 Low Ambient Cooling Lockout Set Point OAT Diff 3 F Low Ambient Cooling Lockout Differential Mechanical cooling will be disabled whenever the outdoor air temperature is less than or equal to the low ambient cooling lockout set point When this occurs the cooling status state will be either Economizer Only or Temperature Enthalpy Disable if all cooling is not disabled for some other reason When the outdoor air temperature rises above the low ambient cooling lockout set point by more than the low ambient cooling lockout differential mechanical cooling will be enabled again Heating Multistage Temperature control Programmable parameters KEYPAD DISPLAY ID Menu Item 12 Heat Cool Heating Spt 70 F Zone Heating Set Point Htg Deadbnd 1 F Zone Heating Deadband Htg PA 8 Min Heating PA Time 14 Htg Control Min Spt 60 Minimum Discharge Heating Set Point Max Spt 120 F Maximum Discharge Heating Set Point Stg Tmr 1 5 min Heating Interstage Timer PARAMETER NAME 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 set point by more than the zone heating deadband value Follo
50. ble parameters KEYPAD DISPLAY ID Menu Item 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 483 MicroTech Applied Rooftop Unit Controller Timed tenant override The tenant override switch provided with several of the zone temperature sensor packages can be used to override unoccupied operation for a preprogrammed time period This time period can be set with the override increment parameter which can be adjusted for any amount of time up to 5 hours in 15 minute increments default is 2 hours When an occupant presses the push button switch on the zone sensor ZNT 1 the override timer menu 25 is set equal to the override increment Note The button must be held for at least 1 second but not more than 30 seconds 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 to operate for another override increment For example assume that the override increment is two hours One press of the override button will provide at least two hours of unit operation If
51. cal cooling as required to maintain the cooling set points Economizer operation will be disabled and the outside air damper will be held at its minimum position This cooling status state is applicable to mixed air and 100 return air units only program ARTS Temperature enthalpy disable When the outside air is too warm for free cooling but too cool for mechanical cooling operation the cooling status state will be Temperature Enthalpy Disable In this state both the economizer and mechanical cooling will be disabled For applications that use an economizer the Temperature Enthalpy Disable state should never occur if the economizer changeover and mechanical cooling lockout set points are adjusted properly If it does occur it may indicate a problem with the external enthalpy control For 0 30 or 100 outdoor air applications the Temperature Enthalpy Disable state will occur when the outside air temperature is below the mechanical cooling low ambient lockout set point Off Unoccupied When the unit is shut down by a scheduling function all cooling will be disabled and the cooling status state will be Off Unoccupied Off Alarm When the unit is shut down by an alarm all cooling will be disabled and the cooling status state will be Off Alarm Manual disable If the cooling status state is Manual Disable it usually means that the control mode menu 11 has been set to one of the following Manual Off Occ Heat Only Occ Fan Only or
52. ccurs the unit will be shut down until the alarm condition is gone and the fault is manually cleared at the keypad Problems have lower priority than faults If a problem occurs the unit will not be shut down but its operation will be modified to compensate for the alarm condition 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 Except for the OA Damper Stuck 1st Filter Dirty and Fnl Filter Dirty alarms a warning will automatically clear when the alarm condition that caused it is gone Alarm priority also exists within each category The alarms in Table 6 are listed according to their priority For example in the fault category the Freeze Shutdown alarm has higher priority than the Sup Sensor Fail alarm OM 109 Page 25 Table 6 CAV ZTC unit alarms ALARM ALARM MESSAGE INDICATION RESET Freeze Shutdown Freeze condition occurred while fans were on Manual Smoke Shutdown Smoke detected at supply air or return air detector Manual Zone Sensor Fail Zone temperature sensor failed while it was the Control Temperature source 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 temp limit setting menu 15 Manual High Supply Temp Sup
53. circuit 1 is lead compressor 1 is lead and when circuit 2 is lead compressor 2 is lead This is true regardless of whether the unit has two or four compressors If the unit is equipped with staging board SB1 the type of lead lag operation must be selected by positioning a jumper plug on the board If the unit is not equipped with staging board SB1 the type of lead lag operation must be selected via either the keypad or PC Caution Automatic lead lag should be used only if the unit has either no hot gas bypass or hot gas bypass on both refrigeration circuits If the unit has hot gas bypass on circuit 1 only the lead lag selection should be set so that circuit 1 is always lead Note On RAH units used with a field supplied condensing unit automatic lead lag should not be used Set the lead lag selection so that circuit 1 is always lead Units without staging board SB1 When the lead cooling circuit parameter is set to 1 circuit 1 will be lead When the lead cooling circuit parameter is set to 2 circuit 2 will be lead When the lead cooling circuit parameter is set to Auto automatic lead lag operation will result OM 109 Page 39 Page 40 OM 109 Units with staging board SB1 Staging board SB1 is shown in Figure 8 When the jumper plug is placed in the JI A LEAD position circuit 1 will be lead When the jumper plug is placed in the J1 B LEAD position circuit 2 will be lead When the j
54. closer to its set point However if the deadband 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 set point 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 Change Algorithm About change The MicroTech unit controller uses the Change algorithm to maintain tight zone temperature control when modulating cooling or heating equipment is being used In response to the Control Temperature Change sets discharge cooling and heating set points that are appropriate for the current zone cooling or OM 109 Page 57 Page 58 OM 109 heating load conditions The Step and Wait algorithm then controls modulating cooling or heating output devices in order to keep the discharge air temperature at or near the Change function s current set point Because Change uses integral control proportional drop load dependent offset is eliminated The tightest possible zone temperature control is the result Following is a general description of Change operation Description of operation CAUTION Grossly misadjusting Step and Wait parameters can cause erratic unit operation and equipment damage Step and Wait parameters should be
55. croTech control system used in the McQuay RoofPak applied rooftop unit product line It specifically describes the sequences of operation and programmable options for units with factory equipped constant volume zone temperature control CAV ZTC equipment and controller software It also includes information on how to use the keypad display to enter and display data For information on MicroTech components input output configurations field wiring options and requirements and service procedures refer to Bulletin No IM 483 Micro Tech Applied Rooftop Unit Controller For installation and start up instructions and general information on a particular rooftop unit refer to its model specific installation manual see Table 1 Table 1 Model specific rooftop unit installation literature INSTALLATION amp MAINTENANCE DATA ROOFTOP UNIT MODEL BULLETIN NUMBER RPS 45 135 tons RFS 45 135 tons IM 485 RCS 45 135 tons RPS 18 40 tons RFS 18 40 tons IM 157 RCS 18 40 tons RDS 800 802 IM 178 WARNING Electric shock hazard Can cause personal injury or equipment damage This equipment must be properly grounded Connections and service to the MicroTech control panel must be performed only by personnel that are knowledgeable in the operation of the equipment being controlled WARNING Excessive moisture in the control panel can cause hazardous working conditions and improper equipment operation When servicing this equipmen
56. d If it is still 54 F outside mechanical cooling should now run N 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 have been corrected the following procedure is used to clear a fault 1 Press ALARMS in the Category group of keys The first menu of the Alarm category is displayed This is menu 29 Curr Alarm The first item of menu 29 is also displayed It probably shows No Active Alarms Assume that a fault exists 2 Press CLEAR in the Action group of keys This clears the alarm and returns the unit to normal operation Modifying a schedule In this exercise assume that a change in building occupancy requires the rooftop 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 this schedule will be changed 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 group of keys The first menu of the Alarm category is displayed This is menu 29 Curr Alarm 2 Press Prev in the Menu group of keys four times Menu 25 Schedule is displayed The first item of this menu Override is also displayed Note that the same result could have been achieve
57. d This alarm can only occur with program ARTS OM 109 Page 51 Page 52 OM 109 High supply temp If the discharge air temperature exceeds 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 temp If the discharge air temperature drops below the low supply temperature limit setting menu 15 while the unit is operational the Low Supply 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 100 return air units program ART5 this alarm will be prevented from occurring until after the recirculate timer expires menu 23 On 100 outdoor air units program ART7 this alarm will be prevented from occurring until after the low supply temperature alarm delay timer expires menu 23 Fan fail If differential pressure switch PC7 fails to detect airflow after the airflow check timer expires the Fan Fail alarm will occur The airflow check timer default is 30 seconds starts timing when the fans start up and when PC7 detects airflow its contacts close If the Fan Fail alarm occurs the unit will be immediately shut down It will remain shut down until the Fan Fail alarm is manually cleared The setting on pressure switch PC7 can be adjus
58. d by starting at the beginning of the Control category of menus and stepping forward to menu 25 by using the NEXT key but it would have taken longer 3 Press Prev in the Item group of keys 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 the same result could have been achieved by stepping forward to Sat by using the NEXT key but it would have taken longer 4 Press ENTER in the Action group of keys 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 this field can be bypassed 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 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 ioe flashing thus completing the edit
59. d 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 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 CLEAR key The CLEAR key is used to clear alarms and edited flashing fields When menu 29 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 serve as a guide through some typical keypad operations Note that often there is more than one way to perform an operation For example the Me
60. de post start up recirculation program ART5 morning warm up operation program ART5 and low supply temperature alarm delay program ART7 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 date time Menu 24 Set Date Time allows the current day date and time to be adjusted For more information see the Scheduling section in the Operator s Guide portion of this manual Schedule Menu 25 Schedule contains the internal scheduling parameters 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 Holiday date Menu 26 Holiday Date allows 14 holiday dates to be scheduled Each date can be assigned a duration from 1 to 5 days On each day of the holiday period the holiday schedule entered under menu 25 is used For more information see the Scheduling section in the Operator s Guide portion of this manual Service Menu 28 Service contains seven service related items The first item Mode allows the unit to be placed
61. e Cooling operation is similar The formula is Calculated Cooling Rate CI Rate OAT Cool OAT Cool Factor The Minutes to occupancy are calculated by dividing the difference between the cooling set point and the space temperature by the Calculated Cooling Rate If Auto Update is selected the parameters will be revised after each start in which they are used and the temperature change is significant Alarm Control Following are descriptions of the various alarms that can occur in CAV ZTC rooftop 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 optional freezestat s FS1 contacts close as a result of detecting an abnormally low water or steam coil temperature while the fans are running If the Freeze Shutdown alarm occurs the MicroTech controller will shut down the fans close the outdoor air dampers open the chilled water and heating valves open the face damper as applicable and set a 10 minute timer When the 10 minute timer expires the controller begins checking the freezestat again If the freezestat s contacts are open the valves and face dampe
62. e controller opens the two position coil valve and modulates the face and bypass dampers as required to maintain the current discharge cooling set point To do this it uses four Step and Wait parameters that are dedicated to mechanical cooling temperature control 1 discharge cooling deadband 2 discharge cooling mod limit 3 discharge cooling wait time and 4 discharge cooling 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 portion of this manual Project ahead The Project Ahead algorithm works to prevent the Control Temperature from overshooting the zone cooling setpoint during periods in which the space temperature is changing Using the cooling PA time parameter the controller anticipates what the Control Temperatures will be if it continues to change at its current rate The controller uses this anticipated Control Temperature as the input to its cooling control processes The result is that the cooling output is increased or decreased early enough to avoid Control Temperature overshoot For most applications the default cooling 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 OM 109 Page 41 Page 42 OM 109 Low ambient cooling lockout Programma
63. e cooling deadband 2 DA set point mod limit 3 DA set point wait time and 4 DA set point 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 If the Change function adjusts the discharge cooling set point up to the maximum discharge cooling set point during occupied periods the controller will leave the Cooling state and enter either Economizer or Fan Only This can only happen if the Control Temperature is less than the zone cooling set point by more than the zone cooling deadband Chilled water valve control When mechanical cooling is operational Cooling or Unoccupied Cooling state the controller modulated the chilled water valve as required to maintain the current discharge cooling set point To do this it uses four Step and Wait parameters that are dedicated to mechanical cooling temperature control 1 discharge cooling deadband 2 discharge cooling mod limit 3 discharge cooling wait time and 4 discharge cooling max step For most applications the default values for theses 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 Chilled water damper control When mechanical cooling is operational Cooling or Unoccupied Cooling state th
64. e difference between the minimum and maximum discharge heating set points menu 14 For example assume that the discharge set point max step parameter is set to 10 the minimum discharge heating set point is set to 60 F the maximum discharge heating set point is set to 100 F In this case the effective max step value for discharge heating control would be 4 F Mod limit The mod limit sets the gain the responsiveness of the control loop to the Control Temperature s deviation from set point The actual amount the discharge cooling or heating set point is either raised or lowered for each wait time period is set in proportion to this deviation The following equation can be used to determine the discharge set point change if the Control Temperature s deviation from set point is less than or equal to the mod limit and greater than the deadband Max S Setpoint Change Deviation from Zone Set Point ee Mod Limit For example assume that the discharge set point mod limit is 10 F and the effective discharge set point max step is 6 F If the Control Temperature is 5 F below the zone heating set point 5 F deviation the discharge heating set point will be raised 3 F If the Control Temperature is above or below the zone set point by more than the mod limit the discharge set point will be raised or lowered by the full max step amount If the Control Temperature is far from set point the set point is rapidly changed and as a result
65. e heating mod limit is 10 F and the discharge heating max step is 10 seconds If the discharge temperature is 6 F above the discharge heating set point the hot water valve will be driven closed for 6 seconds If the controlled variable is above or below the set point 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 set point the actuator is effectively driven continuously This feature assures that the controlled variable will approach its set point as quickly as possible during transient periods for example after unit start up The mod limit parameter s units are the same as the controlled variable s temperature pressure or position Deadband The deadband sets a range in which no control action will be taken If the controlled variable is within the deadband range the actuator will hold its position Note that the deadband parameter s value is added to and subtracted from the set point to determine the deadband range For example if the deadband is 1 F and the set point is 55 F no control action will occur when the controlled variable is 54 F 55 F or 56 F The deadband parameter s units are the same as the controlled variable s temperature pressure or position Typical operating sequence Following is an illustration of Step and Wait control For this example the controlled variable is discharge air temperature and the
66. e occupied heating set points Morning Warm up is similar to the Heating state the difference is that the outside air dampers are held shut The unit will remain in the Morning Warm up state until either the heating load is satisfied or the morning warm up timer menu 23 expires whichever happens first For more information see the Heating Multistage or Heating Modulating section as applicable Heating The Heating operating state occurs when heating is required to satisfy the occupied heating set points During the Heating state the outside air dampers are held at minimum position For more information see the Heating Multistage or Heating Modulating section as applicable Unoccupied economizer program ART5 only If the outside air is suitable for free cooling when purge or night setup operation is required the economizer equipped unit starts and enters the Unoccupied Economizer state During Unoccupied Economizer the outside air dampers are modulated to maintain the current discharge cooling set point The fan output is closed For more information see the Unoccupied Control section Unoccupied cooling When mechanical cooling is required to satisfy the night setup set point during unoccupied periods the unit starts and enters the Unoccupied Cooling state Depending on the outside air enthalpy the economizer s outside air dampers are either fully open or fully closed during Unoccupied Cooling The
67. eating PA time parameter the controller anticipates what the Control Temperatures will be if it continues to change at its current rate The controller uses this anticipated 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 KEYPAD DISPLAY ID PARAMETER NAME Menu Item Programmable parameters 14 Htg Control Max OAT 55 F High Ambient Heating Lockout Set Point High Ambient Heating Lockout Differential Heating will be disabled whenever the outdoor air temperature is greater than or equal to the high ambient heating lockout set point When this occurs the heating status state will be OffOAT Lockout if heating is not disabled for some other reason When the outdoor air temperature drops below the high ambient heating lockout set point 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 KEYPAD DISPLAY ID PARAMETER NAME Menu Item 12 Ht Cl Chgovr Heating Spt 70 Zone Heating Set Point
68. ed operation the 0 30 outside air damper will always be closed Minimum outdoor air damper position control To utilize the fixed minimum outdoor air damper position control strategy set the auto adjust dampers flag to None and set the minimum outdoor airflow set point for the desired minimum damper position External outdoor air damper minimum position reset The minimum outdoor damper position can be reset by a 1 5 VDC or 4 20mA signal across a 249 ohm 1 1 4 watt resistor field signal supplied to analog input 14 To utilize this feature the auto adjust dampers flag is set to External When the external signal is 1 VDC or 4mA the outdoor damper minimum position is set to the Min Airflow value When the external signal is 5 VDC or 20mA the outdoor damper minimum position is reset to the xxx 5VExt value The outdoor damper minimum position will vary linearly between the Min Airflow and xxx 5VExt values as the field signal varies from 1 5 VDC or 4 20mA Note The current minimum outside air position can be displayed through the second item of keypad menu 6 OM 109 Page 37 Page 38 OM 109 Cooling Multistage Temperature control Programmable parameters KEYPAD DISPLAY ID Menu Item 12 Heat Cool Cooling Spt 75 F Zone Cooling Set Point Clg Deadband 1 F Zone Cooling Deadband Clg PA 12 Min Cooling PA Time PARAMETER NAME 13 Clg Control Min Spt 55 F Minimum Discha
69. ensor Prob alarm will automatically clear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller To determine the location of the RAT sensor refer to the Control Locations section of the applicable model specific installation manual see Table 1 Mixd sensor prob If the mixed air temperature sensor MAT fails the Mixd Sensor Prob alarm will occur As a result the unit will continue to operate normally When the alarm condition is gone the Mixd Sensor Prob alarm will automatically clear Note that the MAT sensor is only provided with units that have gas or electric heat Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller To determine the location of the MAT sensor refer to the Control Locations section of the applicable model specific installation manual see Table 1 Heat fail The Heat Fail alarm is applicable only to units equipped with a gas furnace If the pilot flame does not ignite or the flame safeguard FSG control fails to detect a pilot flame within 10 seconds the FSG control will enter the safety lockout state If this occurs relay R24 will energize and close a set of contacts connected to the controller thus causing the Heat Fail alarm As a result the unit will continue to oper
70. er schedule 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 parameter must be set to the desired NMP schedule number 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 Holiday scheduling Programmable parameters KEYPAD DISPLAY ID Menu Item 25 Schedule Hol 00 00 00 00 Holiday Schedule NMP Sched No N A Network Master Panel PARAMETER NAME Schedule 26 Holiday Date Date Dec 25 Holiday Date Dur 1 Days Holiday Date Duration Special operating hours can be scheduled for up to 14 holiday periods by using the controller s holiday scheduling feature 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 holiday date duration parameter For example assume that this year Christmas Eve occurs on a Thursday The 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
71. ere is one Project Ahead parameter that affects the control loop action the PA time Different PA time parameters are used for cooling and heating control At the keypad both of these parameters can be found under menu 12 Heat Cool OM 109 Page 59 McQuay International PA time The PA time defines how much the Control Temperature should be anticipated For example if the heating PA time parameter is set at 8 minutes default the controller would calculate what the Control Temperature will be in 8 minutes and then use that value for it s current heating control processes If the actual Control Temperature had been increasing the anticipated Control Temperature 8 minutes from now would be higher Because the heating control processes use the anticipated Control Temperature the current heating output would be reduced far more than it would if the actual Control Temperature were used To calculate the anticipated Control Temperature the Project Ahead algorithm uses the actual Control Temperature s rate of change over the past five minutes The following equation can be used to determine the anticipated Control Temperature CT Current CT Previous CT Anticipated CT Current CT OS pA Time 5 min For example assume that the unit has recently started and is supplying cooling The current Control Temperature is 78 F and the previous Control Temperature five minutes ago was 80 F The cooling PA time is set at 10 m
72. f any of these devices trip relay R5 or R7 will de energize and open a set of contacts connected to the controller thus causing the Cooling 1 Fail alarm If the alarm is caused by a high pressure condition relay R5 will remain de energized until it is manually reset by cycling switch CS1 If the alarm is caused by a low oil pressure condition relay R5 or R7 will remain de energized until OP1 or OP3 is manually reset MP1 and MP3 will automatically reset when the compressor motor windings cool When R5 and R7 energize again the Cooling 1 Fail alarm will automatically clear For more information refer to the unit wiring diagrams and the Sequences of Operation portion of the model specific installation manual see Table 1 Note that on four compressor units both compressors in circuit 1 will be disabled if either high pressure switch trips However if an oil pressure switch or a motor protector trips only the associated compressor will be disabled In either case the Cooling 1 Fail alarm will occur On units without factory equipped compressorized cooling the digital input used to trigger the Cooling 1 Fail alarm D5 is available for field use If this input senses open contacts the Cooling 1 Fail alarm will occur but unit operation will not be modified in any way The alarm will automatically clear when the contacts close again For more information see the Field Wiring portion of Bulletin No 483 MicroTech Applied Rooftop Uni
73. f heating is enabled menu 8 and there is no zone heating load Fan Only state the controller 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 heating deadband the operating state will change from Fan Only to Fan On Heating Except for the OM 109 Page 47 Page 48 OM 109 discharge set point used Fan On Heating temperature control is identical to that described above for the heating states The Change process is not applicable and for gas heat staging action is controlled by Fan On Heating set point and discharge air temperature deadband instead of the zone temperature parameters If the heating valve or face damper is closed and the supply air temperature rises above the Fan On Heating set point the controller will leave the Fan On Heating state and enter Fan Only Fan On Heating is 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 temperature 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 essential for 100 outdoor air applications in cold climates Return Fan Airflow
74. g Only Temp Ent Disable Off Unoccupied Off Alarm Manual Disable Switch Disable Network Disable Heat Status Heating Allowed Off OAT Lockout Off Unoccupied Off Alarm Manual Disable Switch Disable Network Disable Operating Hours Fan 0 50 000 Hrs Cooling 0 50 000 Hrs Heating 0 50 000 Hrs Override 0 50 000 Hrs Misc Status Enthalpy 21 Outdr Damper Min Type Fan Output This operating state is applicable to program ART5 only This cooling operating state appears only on units with chilled water cooling This cooling operating state appears only on units with DX cooling The wildcard character indicates the current number of active stages The mixed air temperature sensor is factory installed only on units with gas or electric heat This item will appear only on units with program ARTS It is applicable only to units with direct building static pressure control option This item is applicable to program ART5 only This heating operating state appears only on units with hot water or steam heat This heating operating state appears only on units with gas or electric heat The wildcard character indicates the number of active stages Control menus Table 4 lists all possible menus items and adjustable fields in the Control category The table s range column lists all possible values for each adjustable field Following are brief descriptions of the Control
75. gardless of whether the unit is supplying cooling or heating It is caused by a thermal time constant that varies according to the characteristics of the space being controlled Generally the larger the space is the larger the lag effect will be For example consider a large space in which the temperture is falling while the unit is supplying cooling The space would likely overcool without Project Ahead because the unit s cooling output would be reduced too late Now consider the same space in which the temperature is rising while the unit is supply cooling The space would likely overheat without Project Ahead because the unit s cooling output would be increased too late Project Ahead effectively amplifies the effect of the zone temperature control processes only during period in which the Control Temperature is changing As a result the cooling or heating output is increased or decreased early enough to avoid zone set point overshoot Following is a general description of Project Ahead operation Description of operation Project Ahead calculates the rate at which the Control Temperature is changing and increases or decreases the unit s cooling or heating output as required to prevent set point overshoot To do this it uses an anticipated value of Control Temperature instead of the actual Control Temperature as the input to the temperature control processes The anticipated Control Temperature is not available for display Th
76. hat proper discharge 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 on Fan On Heating see the Heating Modulating section Economizer program ART5 only On units equipped with an economizer the Economizer operating state occurs when cooling is required to satisfy the occupied cooling set points and free cooling is available During the Economizer state mechanical cooling and heating are disabled For more information see the Economizer section Cooling When mechanical cooling is required during occupied operation the unit enters the Cooling state Depending on the outside air enthalpy the economizer s outside air dampers are either fully open or at minimum position during Cooling On units equipped with modulating chilled water the unit status display shows Cooling during the Cooling state On units equipped with compressors the unit status display shows 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 program ART5 only The Morning Warm up operating state occurs just after the transition from unoccupied to occupied when heating is required to satisfy th
77. he Control Temperature is within the range above and below the zone heating set point defined by the zone heating deadband the discharge heating set point is held constant Regardless of the zone heating load the Change function will not be allowed to adjust the discharge heating set point outside the range defined by the minimum and maximum discharge heating set points The Change function uses four parameters 1 zone heating deadband 2 DA set point mod limit 3 DA set point wait time and 4 DA set point 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 the minimum discharge heating set point to be set above the zone heating set point This restriction will ensure better zone temperature control during heating operation Note On units with gas heat the controller will not allow the heating discharge set point to be set higher than the current mixed air temperature plus the maximum heat rise value for the heat exchanger This value varies depending on the burner model and baffle arrangement Gas heat Modulating gas heating is actually a three stage process During stage 1 operation the main gas valve is open and the modulating gas valve is continuously driven to its minimum position This is low fire operation During
78. he interference at his or her own expense McQuay International disclaims any liability resulting from any interference or for the correction thereof Software Identification MicroTech Applied Rooftop Unit Controller software is factory installed and tested in each unit prior to shipment The program loaded into the controller is identified by either the software ID or the software part number The software part number is printed on the software ID tag a small label affixed to the control panel next to MCB1 The software ID is encoded in the controller s memory It can be displayed by displaying to the IDENT item under menu 28 Service of the keypad display For information on using the keypad display see the Getting Started portion of this manual Using the keypad display s service menu is the most reliable way of determining the controller s software part number Software part number codification is as follows For more information refer to the Software Identification section of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller 950163 05 D Program Number Version Numeric Version Revision Alphabetical Table 2 shows the two standard software part numbers for the programs used to control CAV ZTC applied rooftop units If the unit s program number does not match one of those listed in Table 2 it is likely that a special program has been loaded into the controller In this
79. hen the Control Temperature is less than the zone heating set point If this is the case the unit controller 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 during Morning Warm up The unit will remain in the Morning Warm up state until either the Control Temperature equals the zone heating set point 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 set point by more than the zone heating deadband when this occurs the controller will enter the Heating state Fan Only state if the unit is cooling only The maximum morning warm up time parameter is provided 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 NAME Menu Item 14 Htg Control Fan On Htg 65 F Fan On Heating Set Point Deadband 1 Discharge Heating Deadband I
80. hus the hot water valve is driven closed for the full duration of the wait time cycle As a result the discharge air temperature drops rapidly Adjusting step and wait parameters Appropriate default Step and Wait parameter values are loaded into each controller at the factory see Table 4 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 operation they can be adjusted If the controlled variable hunts above and below its set point or if it overshoots the set point 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 deadband can also eliminate hunting problems If the controlled variable does not approach its set point 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 Step 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 deadband affects the tightness of control It can be set to a lower value to keep the controlled variable
81. imer default is 30 seconds 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 the applicable model specific installation manual see Table 1 The airflow check timer can be adjusted only with a PC equipped with Monitor software Ist filter dirty If the pressure drop across the first filter exceeds the setting of the pressure switch PC5 while the unit is operational the 1st Filter Dirty alarm will occur Unit operation will not be affected by this alarm The Ist Filter Dirty alarm must be manually reset when the situation has been resolved Fnl filter dirty If the pressure drop across the optional final filter exceeds the setting of the pressure switch PC6 while the unit is operational the Fnl Filter Dirty alarm will occur Unit operation will not be affected by this alarm The Fnl Filter Dirty alarm must be manually reset when the situation has been resolved Misc temp 2 fail If field connected miscellaneous temperature sensor 2 ZNT3 fails the Misc Temp 2 Fail alarm will occur but only if the misc temp 2 present flag is set to Yes This flag can only be set with a PC equipped with Monitor software Unit operation will not be affected by this alarm When the alarm condition is gone the Misc Temp 2 Fail alarm will automatically c
82. imer and then will be modulated to a firing rate that is based on the applicable supply air temperature setpoint the outside air temperature and the maximum temperature rise of the heat exchanger The burner will remain at this firing rate for 30 seconds to allow the heat exchanger to heat up This will all occur during Start up Initialization before the supply fan starts so that warm air is available immediately when the fan is started Note For information on the parameters that affect whether or not heating operation is required refer to the Heating Multistage or Heating Modulating and the Heat Cool Changeover sections of this manual Fan start up mixed air or 100 return air units program ART5 Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME Menu Item PT Fran Delay Timer Pi Aifow Check Timer Recirculate Timer 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 and the outside air dampers remain closed As soon as Recirculate begins the supply fan starts and the following three timers reset and start counting down 1 the fan delay timer 2 the airflow check timer and 3 the recirculate timer When the fan delay timer expires the return fan is started if pre
83. ing or heating required to satisfy the load The source of the Control Temperature can be chosen from among the following selections Space temperature sensor Return temperature sensor program ART5 only Network signal For most applications either the space or return air temperature sensor will be the best Control Temperature source Note that the space sensor must be field installed If the unit controller is included in an Open Protocol network or a MicroTech network that includes an RMC Panel the Control Temperature source can be a network signal With zone temperature control a constant volume of air is delivered at a temperature that is appropriate for the current cooling and heating load Although the Control Temperature ultimately controls the cooling and heating equipment to maintain the zone setpoints discharge temperature limits can override zone temperature control as necessary to maintain acceptable discharge temperatures When cooling is supplied OM 109 Page 33 Page 34 OM 109 the controller will operate the unit to maintain the discharge air temperature within an adjustable cooling range menu 13 When heating is supplied the controller will operate the unit to maintain the discharge air temperature within an adjustable heating range menu 14 Setpoints and deadbands To determine whether to activate the unit s cooling or heating equipment the controller compares the Control Temperature with separate zone
84. int 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 heating set point Note that the controller always sets the discharge heating set point It can be displayed but not changed Note It can be determined 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 Only or Recirculate State the controller sets the discharge heating set point equal to the current supply air temperature menu 2 if the supply air temperature is within the range defined by the minimum and maximum discharge heating set points If the supply air temperatrure is outside this range the discharge heating set point is set equal to the minimum or maximum discharge heating set point When heating control is activated the Change function starts periodically adjusting the discharge heating set point in response to the Control Temperature s deviation from the zone heating set point If the Control Temperature is less than the zone heating set pont by more than the zone heating deadband the discharge heating set point is raised slightly If the Control Temperature is greater than the zone heating set point by more than the zone heating deadband the discharge heating set point is lowered slightly If t
85. into the Shutdown service mode The second item Timers allows most of the controller s process timers to be temporarily sped up For information on these see the Auto Manual Operation section in the Operator s Guide portion of this manual The third item Space Sensor is a setup parameter that specifies whether an optional space temperature sensor is connected to the controller If Space Sensor is set to No the space sensor alarm will be disabled and night setup and setback are not available The fourth item OAT allows the user to select the outside temperature sensor reading location Local sets the reading to be from the unit mounted outside air sensor NMP Remote sets the outside air reading to be from a MicroTech Network Master Panel NMP OPM Remote sets the reading to be from an Open Protocal source The fifth item Alarm Out allows the user to switch the remote alarm output see IM 483 Relay Outputs to an Off indication instead of Blink for BAS compatibility The sixth item Port A Baud allows the user to change the Baud Rate of the controller communication Port A The seventh item IDENT displays the controller s software ID number Table 4 Control menus for programs ART5 and ART7 Name Switch Key Destination Default Shown i Item Name Control Mode Manual Off 1 Unit Status 11 Auto Occupied 12 Heat Cool Cntl Temp Return
86. inutes Using the above equation you can see that the anticipated Control Temperature is 74 F Assume that the zone cooling set point is 75 F and the zone cooling deadband is 1 F In this situation the Change function will stop adjusting the discharge cooling set point and thus the cooling output will stabilize If the actual Control Temperature had been used the Change function would continue lowering the discharge cooling set point the cooling output would increase and the Control Temperature would likely overshoot the zone cooling set point Modulating cooling and heating applications For modulating cooling and heating applications including gas heat Project Ahead is used at all times Staged cooling and heating applications For staged cooling and heating applications Project Ahead is used only when the Control Temperature is far from the zone cooling or heating set point It is enabled when the deviation of the actual Control Temperature from the zone set point is more than 4 F or more than two times the zone deadband whichever is larger Adjusting PA time parameters Default PA time parameter values are loaded into each controller at the factory see Table 4 If the default values do not provide acceptable system operation they can be adjusted Generally the larger the space is the larger the PA time parameter should be Note that the Change algorithm s parameters can also affect zone temperature control If the Control Tem
87. ion 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 3 Control category Menus in the Control category contain set points and parameters 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 summarized in Table 4 Alarm category Menus in the Alarm category contain current and previous alarm information The Alarm category menus are summarized in Table 5 OM 109 Page 5 Page 6 OM 109 Figure 2 Keypad accessible menu structure Category Menu Item Status Menu 1 Item 1 Menu 2 Item 1 Item 2 Ae A Item 8 Menu 10 Item 1 ea Control gt Menu 11 Item 1 Menu 12 Ttem I pe tem Menu 28 Item 1 trem 2 Af Item 7 Alarm gt Menu 29 Item 1 Item 2 Menu 30 Item 1 Item 2 Ae Item 17 Display format The information stored in the MicroTech controller s menu structure can be viewed on the 2 line by 16 character LCD display As shown in Figure 3 the current menu is displayed
88. ion is gone the Zone Sensor Prob alarm will automatically clear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller For more information on the emergency occupied mode see the Unoccupied Control section Note If ZNT1 is not connected to the controller or to disable the Zone Sensor Prob alarm set the space sensor present flag to No menu 28 Zone sensor prob program ART7 If the zone temperature sensor ZNT1 fails while it is not the selected Control Temperature source the Zone Sensor Prob alarm will occur As a result the unit will continue to operate but the night setback and night setup features will be disabled When the alarm condition is gone the Zone Sensor Prob alarm will automatically clear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller Note If ZNT1 is not connected to the controller or to disable the Zone Sensor Prob alarm set the space sensor present flag to No menu 28 Ret sensor prob If the return air temperature sensor RAT fails while it is not the selected Control Temperature source the Ret Sensor Prob alarm will occur As a result the unit will continue to operate but the High Return Temp alarm will be disabled When the alarm condition is gone the Ret S
89. ion reset The minimum outdoor damper position can be reset by a 1 5 VExt or 4 20mA signal across a 249 ohm 1 watt resistor field signal supplied to analog input 14 To utilize this feature the auto adjust dampers flag is set to External When the external signal is 1 VExt or 4mA the outdoor damper minimum position is set to the Min Airflow value When the external signal is 5 VDC or 20mA the outdoor damper minimum position is reset to the xxx 5VExt value The outdoor damper minimum position will vary linearly between the Min Airflow and xxx 5VExt values as the field signal varies from 1 5 VDC or 4 20mA Note The current minimum outside air position can be displayed through the second item of keypad menu 6 0 30 Outside Air Damper Minimum ventilation air volume control Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME Menu Item 21 Outdr Damper Min Airflow 10 Minimum Outdoor Airflow Set Point Min Type None Auto Adjust Dampers Flag XXX 5VExt Maximum Outdoor Airflow Set Point Except during the Morning Warm up state the 0 30 outside air damper will always be controlled to maintain its programmed position during normal occupied operation This is to ensure that a minimum amount of ventilation air will always be supplied to the zones The minimum outdoor airflow set point defines the 0 30 outside air damper position The default value is 10 open During unoccupi
90. isplayed 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 Initialization see the Start up Control section Recirculate program ART5 only The Recirculate operating state begins after Start up Initialization when the fans are 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 Fan only The Fan Only operating state occurs during occupied operation when cooling and heating are either not required or disabled During Fan Only the outside air dampers are at minimum position and cooling and heating are disabled Fan on heating The Fan On Heating operating state is similar to Fan Only The difference is that heating is enabled to prevent the discharge temperature from falling below Fan On Heating set point menu 14 during the Fan On Heating state OM 109 Page 29 Page 30 OM 109 By supplying heat instead of closing the outside air dampers the Fan On Heating state assures t
91. iven fully open during Unoccupied Cooling When the zone temperature drops below the night setup set point by more than the night setup differential the controller will shut down the fans and return to the Off Unoccupied state The default value of this differential is 3 F PC adjustable only After the unit is started cooling equipment control during night setup cooling operation is similar to that during occupied operation Since the Control Temperature is likely well above the zone cooling set point menu 12 cooling control is activated and the cooling output is rapidly increased For more information see the Economizer and Cooling Multistage or Cooling Modulating sections as applicable Purge program ARTS only Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME Menu Item 12 Ht Cl Chgovr Cooling Spt 75 Zone Cooling Set Point Clg Diff 2 F Zone Cooling Deadband 21 Outdr Damper Max Purge 60 Min If a zone temperature sensor ZNT1 is connected to the controller preoccupancy purge control is available on units equipped with an economizer Designed to take advantage of cool pre dawn outside OM 109 Page 49 Page 50 OM 109 air purge control will start the fans and modulate the economizer dampers to maintain occupied cooling requirements during unoccupied periods if conditions are appropriate Purge operation is possible only during a time window prior to occupancy that is set
92. kly determined whether the unit is for example off starting up heating or cooling If heating or cooling is disabled for any reason the reason is displayed Following are descriptions of the possible unit status cooling status and heating status states Unit status The unit status state menu 1 indicates 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 state 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 operation The following operating states are possible Off Start up Initialization Recirculate program ART5 only Fan Only Fan On Heating Economizer program ART5 only Cooling Morning Warm up program ART5 only Heating Unoccupied Economizer program ART5 only 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 Calibrate 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 calibrates the position feedback pot on the outside air damper actuator It also calibrates all the unit s static pressure tra
93. l reset 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 OAT sensor prob If the outdoor air temperature sensor OAT fails the OAT Sensor Prob alarm will occur As a result the unit will continue to operate but the low ambient cooling lockout high ambient heating lockout and purge features will be disabled When the alarm condition is gone the OAT Sensor Prob alarm will automatically clear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller To determine the location of the OAT sensor refer to the Control Locations section of the applicable model specific installation manual see Table 1 Zone sensor prob program ART5 If the zone temperature sensor ZNT1 fails the Zone Sensor Prob alarm will occur As a result the unit will continue to operate but the night setback night setup and purge features will be disabled In addition if the Control Temperature source had been selected to be the zone sensor the controller will automatically change it to the return air sensor If the Zone Sensor Prob alarm occurs during unoccupied periods when the outdoor air temperature is below 40 F the unit will start and run in an emergency occupied mode unless this feature is disabled When the alarm condit
94. lear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller Misc temp 1 fail If field connected miscellaneous temperature sensor 1 ZNT2 fails the Misc Temp 1 Fail alarm will occur but only if the misc temp 1 present flag is set to Yes This flag can only be set with a PC equipped with Monitor software Unit operation will not be affected by this alarm When the alarm condition is gone the Misc Temp 1 Fail alarm will automatically clear Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller Micro Tech DDC Features Step and Wait Algorithm About step and wait The MicroTech unit controller uses the Step and Wait algorithm to control modulating output devices in order to keep a controlled variable at or near the desired set point For example Step and Wait would be used to control a modulating hot water valve in order to maintain the discharge air temperature at or near the discharge heating set point As its name implies Step and Wait steps or modulates an actuator 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 po
95. ly mechanical cooling is enabled Change process Before cooling control is activated Start up Initialization Fan Only or Recirculate State the controller sets the discharge cooling set point equal to the current supply air temperature menu 2 if the supply air temperature is within the range defined by the minimum and maximum discharge cooling set points If the supply air temperatrure is outside this range the discharge cooling set point is set equal to the minimum or maximum discharge cooling set point When cooling control is activated the Change function starts periodically adjusting the discharge cooling set point in response to the Control Temperature s deviation from the zone cooling set point If the Control Temperature is greater than the zone cooling set pont by more than the zone cooling deadband the discharge cooling set point is lowered slightly If the Control Temperature is less than the zone cooling set point by more than the zone cooling deadband the discharge cooling set point is raised slightly If the Control Temperature is within the range above and below the zone cooling set point defined by the zone cooling deadband the discharge cooling set point is held constant Regardless of the zone cooling load the Change function will not be allowed to adjust the discharge cooling set point outside the range defined by the minimum and maximum discharge cooling set points The Change function uses four parameters 1 zon
96. marks in the menu structure the keys in the Category group provide quick access to the desired menus By using these keys 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 ConTrROL 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 is pressed the first menu in the Alarm category is displayed This is menu 29 Curr Alarm SwitcH key The Switch key toggles the display between associated Status and Control category menu items A controlled condition temperature pressure position can be quickly checked against its set point For example by pressing SwitcH when the outdoor damper position is currently being displayed Outdoor Air item under menu 6 the minimum outdoor air setpoint will be displayed Min Airflow item under menu 21 If SWITCH is pressed again the actual outdoor air position will again be displayed Note that the Swircu key will not work with every menu item Tables 3 and 4 list the SwiTcH key destinations for all applicable menu items Menu group The keys in the Menu group allow the desired menu to be displayed Refer to Figure 2 Prev key When the Prev key is pressed the display will scroll to the pre
97. me 1 Min DA Set point Wait Time Max Step 10 DA Set point Max Step 13 Clg Control Setpoint ___ F Discharge Cooling Set Point Min Spt 55 F Minimum Discharge Cooling Set Point Max Spt 65 F Maximum Discharge Cooling Set Point Deadband 1 Discharge Cooling Deadband 21 Outdr Damper Deadband 1 Economizer Deadband Mod Limit 50 F Economizer Mod Limit Wait Time 10 Sec Economizer Wait Time Max Step 10 Sec Economizer Max Step Temperature control Programmable Parameters If the outside air is suitable for free cooling see Changeover Method below the unit controller will attempt to satisfy the cooling load by using outside air before using mechanical cooling If the Control Temperature is greater than the zone cooling set points by more than the zone cooling deadband the controller will enter the Economizer or Unoccupied Economizer state The economizer is controlled in a two part process that constitutes a cascade control loop In one part of the processs the Change function calculates a discharge cooling set point based on the deviation of the Control Temperature from the zone cooling set point It can be displayed but not changed Note It can be determined whether economizer operation is enabled by displaying the cooling status state menu 7 If it is either All Cooling Allowed or Economizer Only economizer cooling operation is enabled Change process Before c
98. mperature 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 KEYPAD DISPLAY ID PARAMETER NAME Menu Item 14 Htg Control Max OAT 55 F High Ambient Heating Lockout Set Point High Ambient Heating Lockout Differential Heating will be disabled whenever the outdoor air temperature is greater than or equal 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 reason When the outdoor air temperature drops below the high ambient heating lockout set point 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 KEYPAD DISPLAY ID PARAMETER NAME Menu Item 12 Ht CI Chgovr Heating Spt 70 Zone Heating Set Point Max MWUP 90 Min Maximum Morning Warm up Time On mixed air units program ART5 morning warm up operation occurs just after the transition from unoccupied to occupied w
99. n start up by the low supply temperature alarm delay timer Its default value is 3 minutes The Low Supply Temp alarm cannot occur until this timer expires This feature will prevent nuisance alarms that might otherwise occur just after start up when the unit s heating equipment is modulating open High turndown gas heat units On units with high turndown gas heat when the unit leaves the Start up Initialization operating state and the supply fan is started the burner will remain at the Start up Initialization firing rate See Before Start up 100 Outdoor Units for four minutes before normal heat modulation begins For information on the parameters that affect normal heating operation refer to the Heating Multistage or Heating Modulating and the Heat Cool Changeover sections of this manual Heat Cool Changeover Temperature control Programmable parameters KEYPAD DISPLAY ID Menu Item 12 Ht Cl Chgovr Cntl Temp Return Control Temperature Source PARAMETER NAME Cooling Spt 75F Zone Cooling Set Point Heating Spt 70 F Zone Heating Set Point Clg Deadband 1 F Zone Cooling Deadband Htg Deadband 1 F Zone Heating Deadband Control temperature The Control Temperature is the representative zone temperature When compared with the zone cooling and heating set points it determines whether the unit will supply cooling heating or neither It also determines the amount of cool
100. nd ART7 cont d Name Switch Key Destination Default Shown No Unocc Htg Clg Cooling Spt 85 F 1 55 99 F 2 Temperatures Space Bldg Pressure Zone Spt 0 050 WC 0 250 0 250 WC 3 Pressures Program ARTS Only Deadbd 0 040 WC 0 000 0 100 WC Mod Lim 0 050 WC 0 002 0 250 WC Wait Time 50 Ten 10 Ten 60 Sec Max Step 50 Ten 10 Ten 60 Sec Outdr Damper Min Airflow 10 0 100 6 Damper Pos Outdoor Air Program ART5 Only Min Type None None 6 Damper Pos Outdoor Air External 0 100 No 9 Misc Status Enthalpy Yes 0 100 F 9 Misc Status Enthalpy 1 9 0 240 Min 0 10 F 1 100 F 1 60 Sec 1 60 Sec 0 255 Sec XXX 5VExt 100 Enthalpy Yes Changeover Chngovr Diff Max Purge Deadband Mod Limit Wait Time Max Step PA Time Timers Recirc Program ART5 Ovrde Inc Max MWUP Timers Low Sat Program ART7 Ovrde Inc 0 59 Set Date Time mm dd yy day hr mn sc 0 59 Schedule Override 0 00 Hr 0 00 5 00 Hr NMP Sched No N A N A 1 32 Sun 00 00 00 00 0 23 0 59 0 23 0 59 00 00 00 00 Same as Sunday 00 00 00 00 Same as Sunday 00 00 00 00 Same as Sunday 00 00 00 00 Same as Sunday 00 00 00 00 Same as Sunday 00 00 00 00 Same as Sunday 00 00 00 00 Same as Sunday Page 14 OM 109 0 00 5 00 Hr 2 60Min 1 12 1 31 0 99 Sun Sat 0 23 T 1 1 1 1 Ab 1 1
101. ng is enabled see note below and outdoor air is either not available or not cool enough to maintain the current cooling load the controller will activate mechanical cooling as it enters the Cooling or Unoccupied Cooling state If there is an economizer and the outdoor air enthalpy is low menu 10 this will normally occur when the outside air damper is more the 95 open and the supply air temperature is above the discharge cooling set point by more than the discharge cooling deadband value If there is no economizer or if the outdoor air enthalpy is high this will always occur when the supply air temperature is above the discharge cooling set point by more than the discharge cooling deadband value Modulating chilled water cooling 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 cooling set point based on the deviation of the Control Temprature from the zone cooling set point In the other part of the process the Step and Wait function modulates cooling output as required to maintain the discharge air temperature at the current discharge cooling set point Note that the controller always sets the discharge cooling set point It can be displayed but not changed Note It can be determined whether mechanical cooling operation is enabled by displaying the cooling status state menu 7 If it is either All Cooling Allowed or Compressors On
102. nomizer o Unoccupied Cooling rina no ves No Unoccupied Heating 100 Flow Yes Notes 1 The fan output will open 3 minutes after the unit enters the Off state 2 This state is not applicable to cooling only units 3 This state is possible only on units that have an economizer 4 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 The 0 30 outside air damper will be at minimum position 5 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 fully closed The 0 30 outside air damper will be fully closed 6 Whenever outside air minimum position is set to 0 and the dampers are at 0 return inlet vanes or VFD are positioned to 100 Variable return fan airflow applies only when unit is configured for optional direct building static control Cooling Morning Warm up Heating Closed Closed Closed Closed Closed No No No No Fan On Heating Minimum Modulating Yes No No YG Ye No Yes Yes Yes Yes Page 28 OM 109 Table 8 Operating states for program ART7 10096 outdoor air OPERATING STATE SUPPLY Adlets HEAT EGH FAN UNIT STATUS FAN AIR ENABLED Cooking OUTRUN DAMPER ENABLED OBA15 Closed
103. nsducers For more information on Calibrate see the following Auto Manual Operation section Cooling status The cooling status state menu 7 indicates whether cooling is enabled or disabled If cooling is disabled the reason is given Following are descriptions of the various cooling status states All cooling allowed When the outside air is cool enough for free cooling but not cool enough to prevent mechanical cooling compressorized or chilled water operation the cooling status state will be All Cooling Allowed In this state the unit will use the economizer mechanical cooling or both as required to maintain the cooling set points On 0 30 or 100 outdoor air units the cooling status state will be All Cooling Allowed when the outside air temperature is above the mechanical cooling low ambient lockout setpoint Economizer only When the outside air is cool enough for free cooling but too cool for mechanical cooling operation the cooling status state will be Economizer Only In this state the unit will use the economizer as required to maintain the cooling set points Mechanical cooling will be disabled This cooling status state is applicable only to units that have an economizer program ARTS Mechanical cooling only When the outside air is too warm for free cooling but not cool enough to prevent mechanical cooling operation the cooling status state will be Mechanical Cooling Only In this state the unit will use mechani
104. ntrol 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 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 483 MicroTech Applied Rooftop Unit Controller To determine the location of the RAT sensor refer to the Control Locations section of the applicable model specific installation manual see Table 1 Sup sensor fail If the supply air temperature sensor SAT fails the Sup Sensor Fail alarm will occur As a result the unit will be shut down It 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 483 MicroTech Applied Rooftop Unit Controller To determine the location of the SAT sensor refer to the Control Locations section of the applicable model specific installation manual see Table 1 High return temp If the return air temperature exceeds 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 cleare
105. nu group keys can be used with or without the optional Category group keys to quickly find the desired menu to be displayed Changing a set point In this exercise assume that the outdoor air temperature is 54 F and mechanical cooling is required It is currently locked out because the low ambient cooling lockout set point is 55 F Using the following procedure the set point will be changed to 50 F and thus enabling mechanical cooling 1 Press CONTROL in the Category group of keys The first menu of the Control category is displayed This is menu 11 Control Mode 2 Press NExT in the Menu group of keys twice Menu 13 Clg Control is displayed The first item of this menu Set Point is also displayed 3 Press NEXT in the Item group of keys once The Min OAT item is displayed This is the low ambient cooling lockout set point The default value of 55 F should also be displayed 4 Press either INCR or DEcR in the Action group of keys The controller prompts for the password 5 Press ENTER in the Action group of keys four times This is the password The Password Verified message is displayed 6 Press DECR until the set point is 50 F Notice that the adjustable field flashes during the change Press ENTER The field stops flashing This means that the new set point is locked in 8 Press SwitcH in the Category group of keys The outdoor air temperature Outdr Air item under menu 2 is displaye
106. occupied Heating state and the furnace is at stage 2 the controller modulates the heating valve as required to maintain the current discharge heating set point To do this it uses four Step and Wait parameters that are dedicated heating temperature control 1 discharge heating deadband 2 discharge heating mod limit 3 discharge heating wait time and 4 discharge 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 portion of this manual If a stage down transition from stage 0 occurs during occupied periods the controller will leave the Heating state and enter Fan Only Like any other stage down transition this can only happen if 1 the heating interstage timer has expired and 2 the Control Temperature is greater than the zone heating set point by more than the zone heating deadband OM 109 Page 45 Page 46 OM 109 Special 100 outdoor air gas heat start up sequence Ifa 100 outdoor air unit is equipped with a high turndown gas furnace and heating is required at unit start up the furnace will enter a special burner start up sequence upon entering Start up Initialization At the beginning of Start up Initialization the burner 90 second pre purge cycle is started simultaneously with a four minute timer The burner will start during this four minute period after the p
107. ool When R6 and R8 energize again the Cooling 2 Fail alarm will automatically clear For more information refer to the unit wiring diagrams and the Sequences of Operation portion of the model specific installation manual see Table 1 Note that on four compressor units both compressors in circuit 2 will be disabled if either high pressure switch trips However if an oil pressure switch or a motor protector trips only the associated compressor will be disabled In either case the Cooling 2 Fail alarm will occur On units without factory equipped compressorized cooling the digital input used to trigger the Cooling 2 Fail alarm D6 is available for field use If this input senses open contacts the Cooling 2 Fail alarm will occur but unit operation will not be modified in any way The alarm will automatically clear when the contacts close again For more information see the Field Wiring portion of Bulletin No 483 MicroTech Applied Rooftop Unit Controller Cooling 1 fail On units with factory equipped compressorized cooling the Cooling 1 Fail alarm will occur whenever one or both compressors in refrigeration circuit 1 are shut down by a safety device or by switch CS1 The following safeties could cause the Cooling 1 Fail alarm compressor motor protector 1 or 3 MP1 or MP3 high pressure switch 1 or 3 HP1 or HP3 and oil pressure switch 1 or 3 OP1 or OP3 MP3 HP3 and OP3 are applicable to four compressor units only I
108. ooling control is activated Fan On or Recirculate state the controller sets the discharge cooling set point equal to the current supply air temperature menu 2 if the supply air temperature is within the range defined by the minimum and maximum discharge cooling set points If the supply air temperature is outside this range the discharge cooling set point is set equal to the minimum or maximum discharge cooling set point When cooling control is activated the Change function starts periodically adjusting the discharge cooling set point in response to the Control Temperature s deviation from the zone cooling set point If the Control Temperature is greater than the zone cooling set point by more than the zone cooling deadband the discharge cooling set point is lowered slightly If the Control Tempertaure is less than the zone cooling set point by more than the zone cooling deadband the dischange cooling set point is raised slightly If the Control Temperature is within the range above and below the zone cooling set point defined by the zone cooling deadband the discharge cooling set point is held constant Regardless of the zone cooling load the Change function will not be allowed to adjust the discharge cooling set point outside the range defined by the minimum and maximum discharge cooling set points The Change function uses four parameters 1 zone cooling deadband 2 DA set point mod limit 3 DA set point wait time and 4 DA set poin
109. 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 suppy air temperature drops below the minimum discharge heating set point by more than the discharge heating deadband during stage 0 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 heating set points For example if the discharge air temperature is below the minimum discharge heating set point stage up condition when the Control Temperature is above the zone heating setpoint by more than the zone heating deadband stage down condition a stage up will occur Note The controller will not allow the minimum discharge heating set point to be set 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 the set point for example just after start up Using the h
110. ot required If the default values do not provide acceptable system operation they can be adjusted Note that the Project Ahead parameters can also affect zone temperature control For information see the following Project Ahead Algorithm section If the Control Temperature hunts above and below its set point or if it overshoots the set point too much during start up or other abrupt changes in unit operation Change control can be slowed down by decreasing the max step value increasing the mod limit value or both Change control can also be slowed down by increasing the wait time however this is not recommended In some cases increasing the deadband can also eliminate hunting problems If the Control Temperature does not approach its set point fast enough during start up or other abrupt changes in unit operation Change control can be speeded up by increasing the max step value decreasing the mod limit value or both The deadband affects the tightness of control It can be set to a lower value to keep the Control Temperature closer to its set point However if the deadband is set too low it can cause hunting in some situations Project Ahead Algorithm About project ahead The MicroTech unit controller uses the Project Ahead algorithm to compensate for the lag effect that is inherent in zone temperature control applications This lag effect can cause the zone temperature to drift above or below the zone set point re
111. perature overshoots its zone set point but then stabilizes fairly quickly after start up or a set point change try increasing the cooling or heating PA time value If the Control Temperature approaches its zone set point too slowly after start up or a set point change try decreasing the cooling or heating PA time value 13600 Industrial Park Boulevard P O Box 1551 Minneapolis MN 55440 USA 612 553 5330
112. ply air temperature exceeded the high supply temp limit setting menu 15 Manual Low Supply Temp Supply air temperature fell below the low supply temp limit setting menu 15 Manual Fan Fail Airflow not proven after the airflow check timer expires default is 30 seconds Manual OA Damper Stuck Outside air damper not at least 50 open after the start up initialization timer expires Manual Freeze Problem Freeze condition occurred while fans were off OAT Sensor Prob Outside air temperature sensor failed while it was not the Control Temperature source V Zone Sensor Prob Zone temperature sensor failed Ret Sensor Prob Return air temperature sensor failed while it was not the Control Temperature source Mixd Sensor Prob Mixed air temperature sensor failed Problem Heat Fail Safety lockout condition occurred in gas furnace Cooling 2 Fail High refrigerant pressure low oil pressure or a compressor motor protector trip condition occurred in refrigeration circuit 2 RPS RDT or RFS RCS units only Cooling 1 Fail High refrigerant pressure low oil pressure or a compressor motor protector trip condition occurred in refrigeration circuit 1 RPS RDT or RFS RCS units only A OA Damper Stuck Outside air damper not fully closed during unit shutdown or not fully open during Manual mechanical cooling operation when outside air enthalpy is low Air Flow Warning Airflow indicated while fans are off Auto Warning 1st Fil
113. program ART5 only Static pressure control Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME 19 Bldg Pressure Zone Spt 0 050 WC Zone Static Pressure Set Point Deadband 0 040 WC Zone Pressure Deadband Mod Lim 0 050 WC Zone Pressure Mod Limit Wait Time 50 Ten Zone Pressure Wait Time Max Step 50 Ten Zone Pressure Max Step On units equipped with the building static pressure control option the MicroTech controller uses the direct building static pressure method to control the return fan airflow With this method the return airflow varies in direct response to the measured building static pressure The result is that proper building pressure is maintained regardless of the building cooling load varying outside air intake or varying exhaust Direct building pressure control can be used for either whole building or lab pressurization positive or negative applications Regardless of the operating state the controller will modulate the return fan airflow as required to maintain the current zone static pressure setpoint whenever the fans are on To do this it uses four Step and Wait parameters that are dedicated to building static pressure control 1 zone pressure deadband 2 zone pressure mod limit 3 zone pressure wait time and 4 zone 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 Algo
114. r will close as applicable If the freezestat s contacts are closed again the valves and face damper will open as applicable and the 10 minute timer will reset The unit will remain shut down until the Freeze Shutdown alarm is manually cleared Smoke shutdown The Smoke Shutdown alarm will occur whenever the contacts of either optional smoke detector SD1 or SD2 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 the applicable model specific installation manual see Table 1 Zone sensor fail If the zone temperature sensor ZNT1 fails while it is the selected Control Temperature source on a 100 outdoor air unit program ART7 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 Note that the unit cao0e quickly restarted by clearing the alarm The Zone Sensor Fail alarm cannot occur on a mixed air or 100 return air unit program ARTS Information on troubleshooting analog input alarms is included in the Test Procedures section of Bulletin No IM 483 MicroTech Applied Rooftop Unit Controller Ret sensor fail If the return air temperature sensor RAT fails while it is the selected Co
115. re purge cycle is complete When the four minute timer expires the burner variable orifice will be modulated to a preheat firing rate according the following formula Preheat Firing Time Variable Orifice Travel Time x Applicable Supply Air Temperature Set Point Outdoor Air Temperature Maximum Heat Exchanger Temperature Rise Where Preheat Firing Time The time increment that the variable orifice increase output relay is energized to achieve preheat firing rate Note 30 seconds is maximum Variable Orifice Travel Time The amount of time it takes the burner variable orifice to drive from fully closed to fully open position 30 seconds Applicable Supply Air Temperature Set Point Either the normal heating supply air temperature set point or the Fan On Heating supply air temperature set point Refer to Discharge Air Low Limit Control for more information on Fan On Heating Maximum Heat Exchanger Temperature Rise The maximum temperature rise across the heat exchanger for safe operation Note This number varies with the size of the heat exchanger and baffle position and is programmed into the controller at the factory Outdoor Air Temperature Current outside air temperature reading This will all occur during Start up Initialization before the supply fan starts so that warm air is available immediately when the fan is stated When the unit leaves the Start up Initialization operating st
116. rge Cooling Set Point Max Spt 65 F Maximum Discharge Cooling Set Point Stg Timer 5 Min Cooling Interstage Timer If the unit is equipped with an economizer and the outside air is suitable for free cooling the unit controller will attempt to satisfy the cooling load by using outside air before using mechanical cooling See the Economizer section above If the unit is not equipped with an economizer the controller will use mechanical cooling whenever cooling is required If mechanical cooling is enabled see note below and outdoor air is either not available or not cool enough to satisfy the current cooling load the controller will activate the first stage of mechanical cooling as it enters the Cooling or Unoccupied Cooling state If there is an economizer and the outdoor air enthalpy is low menu 10 this will normally occur when the outside air damper is more than 95 open and the supply air temperature is above the discharge cooling set point menu 13 by more than the discharge cooling deadband value menu 13 If there is no economizer or if the outdoor air enthalpy is high this will occur when the Control Temperature is above the zone cooling set point by more than the zone cooling deadband value Following is a description of staging operation Note It can be determined whether mechanical cooling operation is enabled by displaying the cooling status state menu 7 If it is either All Cooling Allowed or Compressor
117. rithm section in the MicroTech Control Features portion of this manual Note In any operating state or condition where the outside air dampers are at 0 open such as the recirculate or morning warm up heating the direct building pressure control method is overidden and the return fan will be driven to 100 flow This is to prevent a situation where the outside air is closed and the building static pressure control may have the return vanes at a minimum This would starve the supply fan for air and potentially cause unstable unit operation Unoccupied Control Heating night setback Programmable parameters KEYPAD DISPLAY ID Menu Item PARAMETER NAME 17 Unocc Htg Clg Heating Spt 55 F Night Setup Set Point PP Night Setup Differential If a zone temperature sensor ZNT1 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 operation If the zone temperature falls to the night setback set point when the unit is in the Off Unoccupied state the unit will start up and run If the unit is equipped with factory installed heating equipment the controller will enter the Unoccupied Heating state after start up If the unit is cooling only the controller will enter and remain in the Unoccupied Heating Stage 0 state after start up Field supplied heating equipment would then deliver
118. ry 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 economizer changeover set point 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 set point by more than the changeover differential economizer cooling will be disabled and the outside air dampers will either close unocccupied or go to minimum position occupied Minimum ventilation air volume control Programmable parameters KEYPAD DISPLAY ID Menu Item 21 Outdr Damper Min Airflow 10 Minimum Outdoor Airflow Set Point PARAMETER NAME Min Type None Auto Adjust Dampers Flag XXX 5VExt Maximum Outdoor Airflow Set Point Except during the Morning Warm up state the outside air dampers will always be prevented from closing beyond minimum position during normal occupied operation This is to ensure that a minimum amount of ventilation air will always be supplied to the zones Minimum outdoor air damper position control To utilize the fixed minimum outdoor air damper position control strategy set the auto adjust dampers flag to None and set the minimum outdoor airflow set point for the desired minimum damper position External outdoor air damper minimum posit
119. s Only mechanical cooling is enabled Compressor staging After the cooling interstage timer expires staging occurs as the controller attempts to 1 keep the Control Temperature close to the zone cooling set point and 2 keep the discharge air temperature within the range defined by the minimum and maximum discharge cooling set points After any stage up or stage down action the cooling interstage timer resets and starts counting down again Whenever mechanical cooling is enabled a stage change can only occur after the cooling interstage timer has expired This constraint on compressor staging is essential for preventing short cycling which can reduce compressor life by causing improper oil return and excessive heat buildup in the motor windings It also provides better temperature control Stage up action A stage up can occur for two reasons 1 the Control Temperature is above the zone cooling set point by more than the zone cooling deadband or 2 the discharge air temperature is above the maximum discharge cooling set point Stage down action A stage down can occur for two reasons 1 the Control Temperature is below the zone cooling set point by more than the zone cooling deadband or 2 the discharge air temperature is below the minimum discharge cooling set point Note that a stage down from stage 1 to stage 0 can occur During stage 0 operation all cooling stages are off but the controller remains in the cooling operating
120. sed When three minutes have elapsed the controller records the feedback value of the actuator as equivalent to the fully closed position The feedback voltages should be approximately 5 VDC for the outdoor air damper actuator After the Calibrate procedure is complete the controller places the unit into the Manual Off control mode The unit can be restarted by changing the control mode Service mode Programmable parameters KEYPAD DISPLAY ID PARAMETER NAME 28 Service Mode Normal There are two service modes that can be selected only at the keypad Shutdown and Normal When the Shutdown service mode is selected the unit is placed into the Off Service 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 Unlike the Manual Off control mode selection the Shutdown service mode cannot be overridden by an operator at a remote PC The only way to return the unit to normal operation is to select the Normal service mode at the keypad 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 Caution The service mode can be changed from Shutdown to Normal by an operator at a remote RMC Panel if any To eliminate this risk disconnect unit power or disconnect the communications cable from MCB1 Tenant override Programma
121. sent The fan delay timer s default value is four seconds PC adjustable only On units with the direct building static pressure control option the return fan airflow is modulated to the 100 position The Fan Fail alarm which indicates loss of airflow is prevented from occurring just after fan start up by the airflow check timer Its default value is 30 seconds PC adjustable only The Fan Fail alarm cannot occur until this timer expires Airflow status is sensed by a differential pressure switch PC7 The controller will remain in the Recirculate operating state until the recirculate timer expires Fan start up 10096 outdoor air units program ART7 Programmable parameters KEYPAD DISPLAY ID Menu Item Airflow Check Timer PARAMETER NAME 23 Timers Low SAT 3 Min Low Supply Temp Alarm Delay Timer After the start up initialization timer expires the supply fan starts normal temperature control begins and the following two timers reset and start counting down 1 the airflow check timer and 2 the low supply temperature alarm delay timer The Fan Fail alarm which indicates loss of airflow is prevented from occurring just after fan start up by the airflow check timer Its default value is 30 seconds PC adjustable only The Fan Fail alarm cannot occur until this timer expires Airflow status is sensed by a differential pressure switch PC7 The Low Supply Temp alarm is prevented from occurring just after fa
122. ssible control is the result Following is a general description of Step and Wait operation Description of operation CAUTION 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 the output equipment or controlled variable there are four Step and Wait parameters that regulate the control loop action 1 wait time 2 max step 3 mod limit and 4 deadband Following are descriptions of each parameter and an example of how they work together Refer to Figure 9 OM 109 Page 55 Page 56 OM 109 Figure 9 Typical step and wait operating sequence e Mod Limit SS Na a ee ae ee ee em meee Controlled Variable Supply Air Temperature Se ee a ee ly Oo Soo Sie cae tates Sc i Max Step Max Step Max Step a Step Period I iod ep Perio Wait Period Step Period 0 l Step Period OBA4 _ OBA5 ait Perio t1 ts1 tm t2 tm t3 tm ta 60 of Max Step N a A A M aa Wait Time Wait Time Wait Time Time 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 seconds Max step The
123. t Controller Warnings OA damper stuck program ART5 On units equipped with an economizer the OA Damper Stuck alarm will occur if either of two alarm conditions exists 1 the outside air dampers are more than 5 open three minutes after the controller enters the Off state and 2 the outside air dampers remain less than 95 open when the outdoor enthalpy is low and the controller is in the Cooling or Unoccupied Cooling state Unit operation will not be affected by this alarm but because stuck outside air dampers could be a serious problem during cold weather the OA Damper Stuck alarm must be manually cleared Note that the controller monitors the outside air damper actuator s position and that this value is available for display menu 6 If the outside air dampers appear to open and close completely but the monitored position does not indicate it try having the controller perform the Calibrate procedure For more information on Calibrate see Control Mode in the Auto Manual Operation section of this manual Air flow 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 operation output is energized the controller will prevent the occupied output from de energizing until the alarm clears The airflow check t
124. t during rainy weather the electrical components in the main control panel must be protected from the rain WARNING Compressor pumpdown is required before removing power to the controller or unit damage could occur Z CAUTION 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 ambient temperatures from 40 F to 140 F It is designed to be stored and operated in relative humidity up to 95 non condensing OM 109 Page 3 Page 4 OM 109 A CAUTION 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 It 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 reasonable 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 correct t
125. t 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 If the Change function adjusts the discharge cooling set point up to the maximum discharge cooling set point 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 zone cooling set point by more than the zone cooling deadband Step and wait process When the economizer is operational Economizer or Unoccupied Economizer state the controller modulates the outside air dampers as required to maintain the current discharge cooling set point To do this it uses four Step and Wait parameters that are dedicated to economizer temperature control 1 economizer deadband 2 economizer mod limit 3 economizer wait time and 4 economizer 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 portion of this manual 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 zone cooling set point b
126. taging board compressor lead lag is set with a jumper plug on SB1 instead of menu 16 For more information see the Cooling Multistage section in the Description of Operation portion of this manual Unoccupied heating cooling Menu 17 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 when heating or cooling is required For more information see the Unoccupied Control section in the Description of Operation portion of this manual Note Optional space temperature sensor is required for this feature Building static pressure control On units equipped with program ART5 menu 19 Bldg Pressure contains parameters that are used to vary the return air volume to maintain direct building static pressure control These parameters apply only if the unit has been equipped with the direct building static pressure control option For more information see the Return Fan Airflow section in the Description of Operation portion of this manual Outdoor air damper On units equipped with program ART5 menu 21 Outdr Damper contains parameters that control the optional economizer or 0 3096 outside air damper For more information see the Description of Operation portion of this manual Timers Menu 23 Timers contains adjustable timer settings that control the duration of tenant overri
127. tatus is sensed by PC7 a differential pressure switch Damper position Menu 6 Damper Pos indicates the current outside air damper position and the current outside air damper minimum position setting Cooling status Menu 7 Cool Status indicates which kinds of cooling if any are currently allowed If cooling is disabled it indicates the reason For more information see the Determining Unit Status section in the Operator s Guide portion of this manual Heating status Menu 8 Heat Status indicates whether or not heating is currently allowed If heating is disabled the reason why is indicated For more information see the Determining Unit Status section in the Operator s Guide portion of this manual OM 109 Page 9 Operating hours Menu 9 Operating Hr indicates how many hours the fan cooling heating and override have been operating This information can be used for scheduling maintenance and monitoring unit operation Menu items are Fan Cooling Heating and Override Miscellaneous status Menu 10 Misc Status indicates whether the outside air is suitable for free cooling program ART5 only If it is Enthalpy Low is displayed If not Enthalpy High is displayed Miscellaneous Status also indicates the state of the fan OBA15 output which is available for field connection For more information on this output see the Operating States and Seq
128. ted To determine the location of PC7 refer to the Control Locations section of the applicable model specific installation manual see Table 1 The airflow check timer can be adjusted only with a PC equipped with Monitor software OA Damper Stuck program ART7 If the 100 outdoor air unit s outside air dampers are not at least 50 open after the start up initialization timer expires the OA Damper Stuck alarm will occur As a result the unit will be shut down If the alarm occurs as the timer expires the supply fan will not start The unit will remain shut down until the OA Damper Stuck alarm is manually cleared Note that the controller monitors the outside air damper actuator s position and that this value is available for display menu 6 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 or steam coil temperature while the fans are off If the Freeze Problem alarm occurs the Micro ech controller will open the chilled water and heating valves open the face damper as applicable and set a 10 minute timer When the 10 minute timer expires the controller begins checking the freezestat again If the freezestat s contacts are open the valves and face damper will close as applicable If the freezestat s contacts are closed again the valves and face damper will open as applicable and the 10 minute timer wil
129. ter Dirty Pressure drop across first filter exceeded the setting of PC5 Manual Fnl Filter Dirty Pressure drop across final filter exceeded the setting of PC6 Manual Misc Temp 2 Fail Miscellaneous temperature sensor 2 failed Auto Misc Temp 1 Fail Miscellaneous temperature sensor 1 failed Auto Notes 1 A manual reset is required at smoke detector SD1 or SD2 before the Smoke Shutdown alarm can be cleared 2 A Zone Sensor Fail alarm is applicable only to 100 outdoor air units program ART7 3 This OA Damper Stuck alarm is applicable only to 100 outdoor air units program ART7 4 The Zone Sensor Prob alarm will occur on 100 outdoor air units if the zone temperature sensor fails while it is not the Control Temperature source On mixed air or 100 return air units the Zone Sensor Prob alarm will always occur if the zone sensor fails A manual reset is required at flame safeguard control FSG before the Heat Fail alarm will clear If a high refrigerant pressure condition occurred the cool fail alarm can be reset by cycling the compressor control switch CS1 or CS2 If a low oil pressure condition occurred a manual reset is required at oil pressure switch OP1 OP2 OP3 or OP4 Note that a cool fail alarm will be indicated whenever the compressor control switch CS1 or CS2 is open 7 This OA Damper Stuck alarm is applicable only to mixed air or 100 return air units program ARTS ou Displaying alarms Current alarm
130. to all units depending on the specific unit options The applicable items should be read and understood before making set point or control parameter changes For detailed information on the Step and Wait function which controls the unit s modulating valves and dampers see the MicroTech DDC Features portion of this manual Operating States and Sequences About operating states Operating states define the current overall status of the rooftop system With a single keystroke the operating state can be displayed and the unit s operating condition can be assessed Each operating state summarizes the following information Supply and return fan status Outdoor air damper status Return fan inlet vane or VFD speed status Heating system status Mechanical cooling system status Fan output status Tables 7 and 8 show the operating states and the status information they summarize Table 7 is for CAV ZTC units with program ARTS and Table 8 is for CAV ZTC units with program ART7 Table 7 Operating states for program ARTS mixed air or 100 return air SUPPLY OUTDOOR RETURN MECH FAN PERATING STATE HEAT 2 UNIT Hace RETURN AIR FAN ENABLED COOLING OUTPUT FANS DAMPERS AIRFLOW ENABLED OBA15 OF 100 Flow Start up Initialization Off 100 Flow Recirculate 100 Flow Fan Only On Modulating On On Off No Open No Closed No Closed No Closed i i No Closed o Economizer No coses Closed Wo o Unoccupied Eco
131. trol Figure 6 is for CAV ZTC units with program ART5 and Figure 7 is for CAV ZTC units with program ART7 Depending on the unit options some operating states may not apply Figure 6 Sequence chart for program ARTS mixed air or 100 return air rm eree Start up Initialization Unoccupied Kn si 7 ow es Whee oe ES Heating Unoccupied Cool Recirculate g Unoccupied Morning Economizer Warm up Economizer Cooling Fan On Heating Heating Figure 7 Sequence chart for program ARTZ 100 outdoor air Unoccupied Unoccupied Cooling Heating Start up Initialization Cooling Heating OM 109 Page 31 Page 32 OM 109 Start Up Control A rooftop 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 NAME Menu Item P __ Startup Iniaization Timer When the controller receives a start up command its operating state quickly changes from Off to Start Requested to Start up Initialization During Start up Initialization the fan output OBA15 is closed to indicate that the fans are
132. uences section of this manual and the Field Wiring portion of Bulletin No IM 483 MicroTech Applied Roofiop Unit Controller Table 3 Status menus for programs ART5 and ART7 Switch Key Destination Menu No Unit Status Off Fan Switch 11 Control Mode Off Unoccupied Off Network Off M anual Off Service Off Alarm Start Requested Startup Initial Recirculate Fan Only Fan Only Heat Fan On Htg Stg Economizer Cooling Cooling Stage Morning Warm Up MWUP Htg Stg Heating Heating Stage Unocc Econo Unoccupied Cool Unocc Clg Stg Unoccupied Heating Unocc Htg Stg Calibrate gt 9 gt 9 9 9 gt Temperatures Cntl Temp Same as CT Sensor 12 Ht CI Chgovr Cntl Temp Supply Air 1 240 F 13 Clg Control Set Point Space 1 240 17 Unocc Htg Clg Cooling Spt Return Air 1 240 15 Alarm Limits Hi Return Outdr Air 40 150 F 13 Clg Control Min OAT V MixedAir _ 1 240 Misc T1 1 240 Misc T2 1 240 aa Bldg Pressure Fans Airflow Airflow Supply Fan Return Fan Damper Pos Outdoor Air 0 100 21 Outdr Damper Min Airflow Minimum 0 100 Page 10 OM 109 Table 3 Status menus for programs ART5 and ART7 cont d Switch Key Destination Cool Status All Clg Allowed Economizer Only Mech Cl
133. umper plug is placed in the J2 AUTOLEAD position automatic lead lag operation will result When SB1 is present the controller s lead cooling circuit parameter is ignored Figure 8 Lead lag jumper on staging board SB1 p ooo0oo0oo0o0o00 tg OL J1 B LEAD J J1 A LEAD Ea ro LEAD 000000 TS2 Cooling Modulating Temperature control Programmable parameters KEYPAD DISPLAY ID Menu Item 12 Heat Cool Cooling Spt 75 F Zone Cooling Set Point Clg Deadbnd 1 F Zone Cooling Deadband Clg PA 12 Min Cooling PA Time Mod Limit 10 F DA Set Point Mod Limit Wait Time 1 Min DA Set Point Wait Time Max Step 10 DA Set Point Max Step 13 Clg Control Set Point ___F Discharge Cooling Set Point Min Spt 55F Minimum Discharge Cooling Set Point Max Spt 65 F Maximum Discharge Cooling Set Point Deadband 1 F Discharge Cooling Deadband Mod Limit 20 F Discharge Cooling Mod Limit Wait Time 10 Sec Discharge Cooling Wait Time Max Step 10 Sec Discharge Cooling Max Step PARAMETER NAME If the unit is equipped with an economizer and the outside air is suitable for free cooling the unit controller will attempt to satisfy the cooling load by using outside air before using mechanical cooling See the Economizer section above If the unit is not equipped with an economizer the controller will use mechanical cooling whenever cooling is required If mechanical cooli
134. use the keypad display For information on using the optional monitor software package see the user s manual supplied with the monitor software Using The Keypad Display The keypad display shown in Figure 1 is provided with all MicroTech Applied Rooftop Unit Controllers With the keypad display you can monitor operating conditions system alarms control parameters and schedules After the password has been entered set points parameters and schedules can be edited The optional RMC panel has a keypad display that can emulate the unit mounted keypad display Once the RMC panel s keypad display is interfaced to the desired unit controller it operates exactly the same as the unit mounted keypad display Figure 1 Keypad display 1 Unit Status Economizer CATEGORY MENU ITEM ACTION STATUS ALARMS t t CLEAR PREV PREY INCR NEXT NEXT DECR CONTROL SWITCH 4 4 ENTER Menu structure The keypad accessible information in the MicroTech controller 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 information on the contents of each menu is included in the following Keypad Display Menu Reference sect
135. vious menu in the structure This action will occur regardless of the current menu number Note that the display will wrap around from the first menu to the last menu when the Prev key is pressed twice Next key When the Next key is pressed the display will scroll to the next menu in the structure This action will occur regardless of the current menu number Note that the display will wrap around from the last menu to the first menu when the NEXT key is pressed twice Item group Once a menu is selected the item to be displayed is chosen by using the keys in the Item group Refer to Figure 2 Prev key When the Prev key is pressed the display will scroll to the previous item in the current menu Note that the display will wrap around from the first item to the last item when the Prev key is pressed twice Next key When the Next key is pressed the display will scroll to the next item in the current menu Note that the display will wrap around from the last item to the first item when the NEXT key is pressed twice Action group The Action group keys are used to clear alarms or change set points and parameters in the selected item s field s Note that the password must be entered before any set point parameter or schedule changes can be made See Password Protection above for more information OM 109 Page 7 Page 8 OM 109 Incr key When the Incr key is pressed the entry in the item s selected fiel
136. wing is a description of operation Note It can be determined 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 Stg Tmr 1 expires staging occurs as the controller attempts to 1 keep the Control Temperature close to the zone heating set point and 2 keep the discharge air temperature within the range defined by the minimum and maximum discharge heating set points After any stage up or stage down action the heating interstage timer resets and starts counting down again Whenever heating is enabled 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 provides better temperature control Stage up action A stage up can occur for two reasons 1 the Control Temperature is below the zone cooling set point by more than the zone heating deadband or 2 the discharge air temperature is below the minimum discharge heating set point Stage down action A stage down can occur for two reasons 1 the Control Temperature is above the zone heating set point by more than the zone heating deadband or 2 the discharge air temperature is above the maximum discharge heating set point Note that a stage down from stage 1 to stage 0 can occur During stage 0
137. with the purge time parameter 0 to 240 minutes For example if unit start up is scheduled for 6 30 a m a purge time of 60 minutes default would allow purge operation to occur between 5 30 a m and 6 30 a m Note that purge control will work in conjunction with any scheduling method except an external time clock During the purge time window the unit will start and run whenever the following three requirements are all met The space temperature is greater than the zone cooling set point by more than the zone cooling deadband e The outside air enthalpy is low enough to enable the economizer The outside air temperature is below the space temperature by more than 3 F During purge operation the controller will enter and remain in the Unoccupied Economizer operating state after normal start up Mechanical cooling is disabled Economizer control during purge operation is similar to that during occupied operation The only difference is that there is no minimum outside air damper position control The controller will shut down the unit and return to the Off Unoccupied state whenever any of the following three conditions occur The space temperature is below the zone cooling set point by more than the zone cooling deadband The outside air enthalpy is high The outside air temperature is not below the space temperature by more than 2 F As conditions allow purge control will cycle the unit in this manner until normal occupied
138. y Schedule Fri 00 00 00 00 Friday Schedule Sat 00 00 00 00 Saturday Schedule Hol 00 00 00 00 Holiday Schedule NMP Sched No N A Network Master Panel Schedule When the unit is in the Auto control mode menu 11 and it is not disabled the unit will start and stop according to the controller s internal schedule One start and one stop time can be set 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 manual 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 __ Stop Minute Mon 06 30 18 00 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 To schedule a unit to shut down and then start up again on the same day requires 1 an NMP schedule 2 an external time clock or 3 a combination of scheduling methods for example an RMC schedule and a unit controll
139. y more than the zone cooling deadband Project ahead The Project Ahead algorithm works to prevent the Control Temperature from overshooting the zone cooling set point during periods in which the space temperature is changing Using the cooling PA time parameter the controller anticipates what the Control Temperature will be if it continues to change at its current rate The controller uses this anticipated Control Temperature as the input to its cooling control processes The result is that the cooling output is increased or decreased eary enough to avoid Control Temperature overshoot For most applications the default cooling 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 OM 109 Page 35 Page 36 OM 109 Mechanical Cooling If the outdoor air enthalpy menu 10 changes from low to high at any time while the economizer is operational Eonomizer or Unoccupied Economizer state the transition from economizer operation to mechancial cooling operation will occur During occupied operation the outside air dampers will be driven to the current minimum position 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 outside

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