RM Series User`s Manual
Contents
1. OFF or intheminimum economizer position the power exhaust is off As the economizer begins to modulate open an end switch adjustable closes which starts the power exhaust fan motor The amount of exhaust air is controlled by a set of dampers in response to the unit mounted building static pressure controller The power exhaust operates until the economizer modu lates below the end switch setting or the unit is shut off NOTE Static pressure sensing tubing is field supplied and installed 14 Il VAV Variable Air Volume SYSTEMS NOTE VAV BOXES AND CONTROLS ARE SUPPLIED BY OTHERSFORFIELDINSTALLATION When a call for cooling is received the controller board stages on compressors to maintain a field set supply air temperature As different zones become satisfied their VAV boxes will close This in turn causesthesupply duct pressure to rise The VAV controller board senses this increasein pressure and modulates the supply fan speed to maintain the required field set supply air pressure setpoint Normally VAV units are cooling only units There are certain applications where electric or gas heat is used to provide morning warmup When gas or electric heat is used for morning warmup the airflow will not be allowed tovary Thefan speed control will bedisabled until a call for cooling is received then the heating system will be locked out and VAV will be enabled IIl POWER EXHAUST OPTIONS When space over pressurization occurs2. STEAM OR HOT WATER HEATING SYSTEM Heating is accomplished by passing steam or hot water through the steam or hot water coil assembly COOLING SECTION DX All direct expansion refrigeration systems are factory assembled charged with refrigerant tested and oper ated On all units 8 ton and larger the refrigerant system indudes multiple circuit evaporator and con denser coils providing two or more stages of cooling Thesesystems are provided with liquid linefilter driers expansion valves and fully hermetic compressors Compressors are equipped with a positive pressure forced lubrication system PERIODIC INSPECTION PROCEDURES GAS HEATING UNITS 1 The flow of combustion and ventilating cannot beobstructedin any way Theindoor blower evaporator coil and filters must be inspected monthly 2 Once each year prior to the heating season a qualified technician must inspect all flue product carry ingareas of thefurnace and main burners for continued safe operation WARNING At least once each year a qualified ser vice technician should check out all of the items listed under the servicing and trouble shooting and mainte Heat Exchanger prior to installation in unit nance section of this manual Note dimple construction 3 If the induced draft blower motor assembly re quires replacement an airtight seal between the blower housing and the burner box must be restored High temperature silicone sealant must be used to ensure a
3. due to econo mizer operation a power exhaust will be utilized to provide relief A When three position economizer is called for an On Off power exhaust will be used POWER EXHAUST w 3 POSITION ECON In the unit OFF or in the minimum economizer position the power exhaust fan is off When theunit goes to 100 outside air operation the power exhaust fan motor starts and operates until the unit is shut off or the economizer goes back to minimum position The end switch located on the economizer outside air damper section is field adjustabletoallow for differences in building design The switch engages and disengages the power exhaust motor s through acontactor Theend switch is included in the 24 VAC circuit B Full modulating economizer a full modulating power exhaust will control the amount of actual exhausted air by means of a building sensing pressure control which opens or doses according to desired pressure in the space 15 RM SERIES USERS INFORMATION MANUAL AAON Inc 2425 South Yukon Tulsa Oklahoma 74107 ph 918 583 2266 fax 918 583 6094 R15700 7 03
4. by hand BEFORE OPERATING smell all around the appliance area for gas Be sure to smell next to the floor because some gas is heavier than air and will settle on the floor WHAT TO DO IF YOU SMELL GAS Do not try to light any appliance Do not touch any electric switch do not use any phone in your building Immediately call your gas supplier from a neighbor s phone Follow the gas supplier s instructions OPERATING INSTRUCTIONS Open control access panel Push in gas control knob slightly and turn clockwise to OFF NOTE Knob cannot be turned to OFF unless knob is pushed in slightly Do not force WAIT five 5 minutes to clear out any gas Then smell for gas including near the floor If you smell gas STOP Follow B in the safety information above on this label If you don t smell gas goto the next step Turn gas control knob counterclockwise VON to ON Close control access panel Turn on all electric power to the appliance Set thermostat to desired setting If the appliance will not operate follow the instructions To Turn Off Gas To Appliance and call your service technician or gas supplier STOP Read the safety information above this label Set the thermostat to lowest setting Turn off all electric power to the appliance This appliance is equipped with an ignition device which automatically lights the burner Do not try to light the pilot by hand GAS CONTROL KNOB SHOWN IN ON POSITIO
5. filters will result in a clogged evaporator coil a very expensive service prob lem to resolve B OBSTRUCTION TO AIR FLOW Supply and return air grilles must be kept dear so air can be freely discharged from and drawn into the system FILTER INSTALLATION REPLACE MENT Before inspecting or replacing the filters be sure the A WARNING unit 1S NOT operating The filters are located in the filter access section of the unit Open filter access door Before attempting to perform any service and pull filters straight out to inspect Inspect ALL or maintenance tum the electrical power filters each time Replace filters with the size indicated to unit to OFF at disconnect switch es on each filter or as shown in thefilter chart below Arrow on replacement filters must point towards the blower have multiple power supplies Monthly inspection is required to maintain optimum efficiency ITISIMPORTANT KEEP COILS BLOWER AND FILTERS CLEAN Slide out filters Optional Economizer Optional R A smoke detector location NOTE CHART REFLECTS STANDARD FACTORY SUPPLIED FILTERS AND SIZES CONTACT FACTORY FOR SPECIAL OPTIONAL FILTER PACKAGES FILTERS UNIT SIZE 16 20 Standard 2 Throwaway 16 x 20 Optional 2 or 4 Pleated 20 x 25 Optional 2 or 4 Pleated FILTERS SHOULD BE REPLACED EVERY 30 DAYS OR AS REQUIRED POSSIBLE CAUSE SERVICING TROUBLE ELECTRIC HEATING Che
6. heat The vent motor should operate The control will automatically supply energy to the spark gap and the gas valve after the thermostat contact closes 4 Thesensing probe detects the presence of the flame Should no flame be detected in 10 seconds the ignition system will recycle If noflameis detected in 3tries the ignition system will lockout 5 Adjust thermostat to a low temperature setting to open contacts The main gas flames should be extinguished NOTE The evaporator blower is controlled by the ignition system In the fan Auto mode the blower comes on 45 seconds after flame is proved and goes off 120 seconds after the thermostat opens SERVICING TROUBLE SHOOTING amp MAINTENANCE ELECTRIC SHOCK HAZARD Shut off all electrical power to unit to avoid shock hazard or injury from rotating parts CLEANING Inspect unit interior at the beginning of each heating and cooling season and as operating conditions require COILS Evaporator coil s should be inspected and cleaned an nually to ensure there is no obstruction to air flow Condenser coil s should be inspected monthly Clean condenser coils annually or as required by location and outdoor air conditions CONDENSATE DRAIN Check and clean annually at start of cooling season BLOWER Inspect blower and blower section to keep free of dust or debris TURN OFF POWER BEFORE ATTEMPTING TO CLEAN BLOWER WHEEL Typical slide out blower section LUBRICA
7. water control valves operation Check water temperature rise entering and leaving unit to determine if adequate water is flowing 1 1 Contactor not closing Motor failed SYSTEM OFF EVAPORATOR BLOWER WILL NOT RUN FAN MOTOR RUNS HOT AND CUTS OUT BLOWER DOES NOT DELIVER AIR BLOWER COMES ON BUT LITTLE OR NO COOLING ROOFTOP UNIT REPLACEMENT PARTS Replacement parts for AAON equipment may be obtained from AAON When ordering parts always referencethe unit model number serial number and part number AAON Inc Customer Service Department 2425 South Yukon Ave Tulsa Oklahoma 74107 Phone 918 583 2266 Fax 918 382 6364 ALWAYS USE AAON SPECIFIED PARTS 12 SEQUENCE OF OPERATIONS B COOLING 1 Packaged Units When thethermostat calls for cooling from 650866 Y 1 makes R to CC1 through theLPS low pressureswitch HPS high pressure switch and optional GOT guaran tee off timer 2 DX Only Coil Units When thethermostat calls for cooling from the space the condensing unit is energized refer to manufacturers instructions for sequence of operation The evaporator blower contactor is energized simultaneously with the condensing section 3 Chilled Water Coil Units Theblower contactor is energized toprovidesupply air on asignal fromthespacethermostat All other controls are by others C OPTIONAL ECONOMIZER When cooling is called for and the unit has the econo mizer option installe
8. N GAS INLET i TO TURN OFF GAS TO APPLIANCE ME 4 Pushin gas control knob slightly and turn clockwise X to OFF Do not force Close control access panel Theair cooled condenser coil s areconstructed of copper tubes and mechanically bonded aluminum fins and air pulled through by propeller fans The evaporator coil is draw through type constructed of copper tubes and mechanically bonded aluminum fins The refrigeration section of these appliances has been found acceptable with applicable provisions of ANSI UL 1995 and current C S A Standard C22 2 byE T L NOTE Crankcase Heater Operation Some units are equipped with a compressor crankcase heater which should beenergized at least 24 hours prior to setting the thermostat for cooling operation COOLING SECTION CHILLED WATER or NON COMPRESSORI ZED UNIT Chilled water or non compressorized units havefactory installed coils Systems are provided with internal header connections for field piping Coils are con structed of copper tubes and mechanically bonded alu minum fins 5 Set the thermostat to lowest setting Turn off all electric power to the appliance if service is to be performed Open control access panel ELECTRIC HEATING SYSTEM Heating is accomplished by passing electrical current through a specified amount of resistance heaters which produce the required heat The indoor blower motor energizes at the same time as the heaters
9. RM SERIES AAON HEATING COOLING amp COMBINATION ROOFTOP UNITS USERS INFORMATION MANUAL 7 2003 FOR YOUR SAFETY WHATTO DO IF YOU SMELL GAS EXTINGUISH ANY OPEN FLAME 7 DO NOTTOUCH ANY ELECTRICAL SWITCH DO NOTTRY TO LIGHTANY APPLIANCE e DO NOTUSE ANY PHONE IN YOUR BUILDING e IMMEDIATELY CALL YOUR GAS SUPPLIER FROM A NEIGHBOR S PHONE FOLLOW THE GAS SUPPLIER S INSTRUC TIO NS e IF YOU CANNOTREACH YOUR GAS SUPPLIER CALL THE ARE DEPARTMENT NE NS Ifthe information in this manual is not followed exactly a fire orexplosion may resultcausing property damage personalinjury orlossoflife FOR YOUR SAFETY DO NOTSTORE OR USE GASOLINE OR OTHER FLAMMABLE VAPORS AND LIQUIDS IN THE VICINITY OF THIS OR ANY OTHER APPLIANCE AAON TABLE OF CONTENTS SECTION PAGE NUMBER OWNERS INFORMATION coti breit Dr npe braune Ead 3 4 HEATINGZ7COOLING SYSTEMS 4 5 Gas Unit Lighting Instructions PERIODIC INSPECTION 6 6 7 SERVICE TROUBLE SHOOTING amp MAINTENANCE 8 Lubrication Cleaning FILTER INSTALLATION REPLACEMENT 9 e 10 12 Rooftop Unit Replacement Parts SEQUENCE OF OPERATIONS dina 13 Heating Cooling Optional Ec
10. RUCTIONS IF REMOTE CONDENSER Motor run capacitor open or shorted Overload thermal protector open in motor Relay not closing Motor failed Capacitor shorted or open PSC motors only Stuck shaft or blower wheel Check for low refrigeration charge Compressor overload setting Ambient temperature too low Filters dirty or air flow restricted Evaporator blower not running REFER TO MFG S INSTRUCTIONS IF REMOTE CONDENSER Line voltage too high REFER TO MFG S INSTRUCTIONS IF REMOTE CONDENSER Blower running backwards Dirty filters Duct obstruction Belts loose if applicable Motor failed Fan or shaft stuck Line voltage too low Limit switches are open Overload or pressure control tripped pwne 5 11 SYSTEM OFF CONDENSER FAN WILL NOT RUN EVAPORATOR BLOWER WILL NOT RUN COMPRESSOR SHORT CYCLES FAN MOTOR RUNS HOT AND CUTS OUT COMPRESSOR WILL NOT START BLOWER DOES NOT DELIVER AIR POSSIBLE CAUSE SERVICING Continued TROUBLE COOLING CHILLED WATER Check power at line side of contactor s 2 Thermostat not set for cooling Overload thermal protector open in motor Line voltage too high Blower running backwards Dirty air filters Duct obstruction Belt loose if applicable Check supply water and temperature Check
11. S LIFE IMPORTANT NOTICE All gas fired heat exchangers are completely tested at the factory before shipment This will remove nearly all of the oils that have been used in the manufacturing process however trace amounts may remain When performing the initial start up at the jobsite it is highly recommended that people or any other living animals that may besensitivetotheresidual odors or gases NOT be present in the conditioned space during the start up In all cases including the initial factory firing and testing any of the gases will be under the acceptable level of concentration for human occupancy NOTE Incaseemergency shut down is required turn off the main manual gas shut off valve and disconnect main electrical power to unit These devices should be properly labeled by the installer GAS HEATING SYSTEM The heating section is for use with natural gas supply pressureof 6 to10 5 Water Column Theunit may also utilize propane gas with a supply pressure to the valve of 11 to 12 Water Column The rating plate on the furnace must be inspected to make sure the unit is stamped for proper gas A 1 8 pressuretap should be field supplied by theinstaller in the piping just ahead of thegas valve Thepressuretap on the outlet end of the gas valve can be checked to verify manifold pressure of 3 2 to 3 5 for natural gas Combustion air is supplied by a centrifugal blower which draws in outside air through a protected opening This
12. TION All original blower motors and bearings are furnished with an orginal factory charge of lubrication Some applications will require that bearings be re lubricated periodically Theschedule will depend on the operating duty temperaturevariations other harsh atmospheric conditions Bearings should be re lubricated when at normal oper ating temperatures but not during operation Rotate the fan shaft manually and add minimum lubricant requiredtopurgetheseals DONOT OVERLUBRICATE Recommended lubricants are SHELL OIL DOLIUM CHEVRON OIL SRI No 2 TEXACO INC PREMIUM RB SERVICE If the unit does not function properly and service is required servicetechnicians qualified and experienced in both gas electric heating and air conditioning are permitted to provideservice tokeep warranties effect The service technician should call the factory if assis tance is required SERVICE TECHNICIAN MUST PROVIDE THE MODEL AND SERIAL NUMBER OF THE SPECIFIC UNIT TO CUSTOMER SERVICE TO ASSURE A COR RECT DIAGNOSIS AAON Inc Phone 918 583 2266 Fax 918 382 6364 Customer Service Department COMMON CAUSES OF REDUCED AIR FLOW A DIRTY FILTERS Filters must beinspected and replaced on a regular basis It is strongly recommended that the media be replaced monthly Clean filters are your best protection against premature system break down Do not operate the unit without the filters in place Operation of the unit without
13. ch to OFF Set the thermostat fan switch to AUTO Do not change temperature setting With these settings the system is shut down with the exception of the control system power 24 Vac and the crankcase heater of the compressor approx 60W DO NOT TURN OFF THE MAIN POWER SWITCH NIGHT AND VACANT WEEKEND OPERATION Toreduce the operation time during low load periods it is recommended that the temperature setting be increased fivedegrees duringthese periods of thecooling season and decreased ten degrees during the heating season GAS UNIT LIGHTING INSTRUCTIONS WE FOR YOUR SAFETY READ BEFORE OPERATING IF YOU DO NOT FOLLOW THESE INSTRUCTIONS EXACTLY A FIRE OR EXPLOSION MAY WARNING RESULT CAUSING PROPERTY DAMAGE PERSONAL INJURY OR LOSS OF LIFE If you cannot reach your gas supplier call the fire department Use only your hand to push in or turn the gas control knob Never use tools If the knob will not push in or turn by hand don t try to repair it call a qualified service technician Force or attempted repair may result in a fire or explosion Do not use this appliance if any part has been under water Immediately call a qualified service technician to inspect the appliance and to replace any part of the control system and any gas control which has been under water This appliance does not have a pilot It is equipped with an ignition device which automatically lights the burner Do not try to light the pilot
14. ck power at line side of contactor s Thermostat not set for heating Overload relay tripped Heater Relay not energized Blower Contactor not energized Capacitor shorted or open PSC motors only Blower running backwards Dirty air filters Dirty coils Duct obstruction Belts loose if applicable One or more heater contactors are open Limit switches are open Heater relay open Heat strips burned out GAS HEATING Check power and gas supply Check thermostat switches and settings Check 24 volt power to ignition control Check for power at main gas valve Defective gas valve Loose or broken connection to gas valve Check limit controls for open Check continuity of differential pressure switch with motor turning If open replace differential pressure switch Defective ignition control Thermostat not calling for heat Relay not closing No power to motor Motor stuck or winding open Internal motor overload open Unit blower not coming on Check fan control Blower motor running backward Filters dirty Ducts obstructed or dampers closed Manifold gas pressure too high Hand valve off turn to on main gas valve Gas off or very low pressure Check for power at main gas valve Check continuity of differential pressure switch with motor turning If open replace differential pressure switch Sparker sensor out of adju
15. control compartment door CONDENSATE PIPING A drain trap is to be connected tothe drainpan If codes require a condensate drain line it should be the same pipesizeas thedrain nippleand should pitch downward toward drain The condensate drain pipe P trap is factory supplied and shi pped in the control access compartment for field installation An air break should beused with long runs 3 of condensate lines Theunitsaredesignedas self contained heating cooling or combination units for outdoor installation only using therefrigerant shown on therating plate chilled water natural or propane gas elecricresistance steam or hot water heating WARNING Failuretoobservethe following instructions will result in premature failure of your system and possible void ing of the warranty DIRECT EXPANSION DX COOLING UNITS Never cut off the main power supply to the unit except for complete shutdown When power is cut off from the unit compressors with crankcase heaters cannot pre vent refrigerant migration The compressor will cool down and liquid refrigerant will accumulate in the compressor The compressor is designed to pump only refrigerant gas and damage may occur when power is restored If power must be cut off for more than an hour turn the thermostat system switch to OF F and leaveit off until the main power switch has been turned on again for at least twenty four hours on units with compressor crank case heaters Thi
16. d temperature switch ECS or En thalpy allows the economizer operation when the out side air reachestherequired setpoint Some options use dry bulb sensing and some options use enthalpy sensing to determine the outside air O A condition When the economizer is in operation Y 1 controls the opening and closing of the dampers Y2 is then able to control the compressors which Y 1 normally controls A modulating economizer is also available The operation is the same as the standard economizer except that the motor modulates the damper position to maintain a preset mixed air temperature 13 GENERAL INFORMATION A HEATING 1 Natural Gas When the thermostat calls for heating W1 makes to the heat relay HR All N O Normally open contacts close and all N C normally closed contacts open The combustion motor starts and asthepressuredecreases in the flue outlet box the ignition control is energized The control sends 24 VAC to the main gas valve and high voltagetotheignitor If aburnerflamehas been detected after 10 seconds thespark is extinguished and theflame continues If a flame has not been detected after 10 seconds the gas valve closes the spark ceases and the induced draft blower continues to purge the heat ex changer After 45 seconds of purge the ignition system will attempt tolight the burners again Should noflame bedetected after 3 attempts theignition control locks out the system On a fault the gas t
17. good seal 4 GAS BURNERS THE BURNERS SHOULD NEVER REQUIRE CLEANING If cleaning is necessary it indicates faulty operation of theunit Thecleaning should bedoneonly by a qualified serviceagency after consultation with an AAON Service Representative Itisrecommendedthat if thegas burners requirecleaning call an AAON Service Engineer at 918 583 2266 5 HEAT EXCHANGER The necessity for cleaning the exchanger could indicate i faulty operation and should only be checked by a quali fied service agency after they have discussed the Combustion Motor Fue Outat lem with a Service Representative Burner Assembly PERIODIC INSPECTION PROCEDURES Continued HEATING ELECTRIC 1 Set thermostat in the heat mode 2 Set thermostat to call for heat to engage all electric heat strips Check blower for proper rotation and voltage 3 Measurethe amperage and voltage Comparethem to the nameplate data HEATING STEAM OR HOT WATER 1 Set thermostat in the heat mode 2 Check supply blower for proper rotation and voltage 3 Check boiler or hot water operationsaccordingtothe manufacturer s instructions and recommendations 4 Check control flow valves for correct operation and settings according to the manufacturer s instruc tions and recommendations ELECTRIC STEAM HOT WATER COOLING amp CHILLED WATER UNITS 1 Blower coilsandfiltersshould beinspected monthly 2 Oncea year beforeunit is turned o
18. induced draft blower introduces the air to the burner tubes which assures even primary and secondary air flow All heating system and related safety controls are 10096 tested on each unit prior to shipment The units are equipped with a direct spark ignition system which proves the burner operation during each call for heat Power tothe ignition control is 24 Vacto reduce hazards Burner ignition is by a high intensity spark When heat is called for the cooling system is inoperable except for the indoor blower motor Heating is accom plished by firing gas into the heat exchanger assembly OWNERS INFORMATION continued Those sensitive to odors or gases from trace amounts of residual oils should NOTbe present in the conditioned space during the startup ofa gas fired installation HEATING amp COOLING SYSTEMS NORMAL OPERATION HEATING Set the thermostat system switch to HEAT Set the thermostat fan switch to AUTO or ON Set the thermostat temperature at the desired point COOLING Set the thermostat system switch to COOL Set the thermostat fan switch to AUTO or ON Set the thermostat temperature at the desired point AIR CIRCULATION Set the thermostat system switch to OFF Set the thermostat fan switch to ON Do not change temperature setting With these settings the air circulating blower will run continuously but the air will not be heated or cooled SYSTEM OFF Set the thermostat system swit
19. n for the heating season a qualified servicetechnician should inspect the unit for proper operation 3 All valves and steam traps should be inspected according to the manufacturer s instructions and recommendations WARNING of the items listed under the service troubleshooti ngand maintenancesecti on of this manual should be performed once a year Hectric shock hazard Can cause injury or death Before attempting to perform any service or maintenance tum the electrical power to unit to OFF at disconnect switc h es Unit may have multiple power supplies COOLING 1 Main Power Switches are on and power is to the unit 2 Set thermostat in cooling mode and place the fan switch to on Check blower for correct operating direction amperage and voltage 3 PACKAGED UNITS Check compressor s operation Check the amperage and comparetothe nameplate data check amperage load side of the compressor contactor 4 DX COIL UNITS If applicable check remote con denser as per the manufacturer s recommendations 5 CHILLED WATER UNITS Check remote chiller operations as per the manufacturers instructions Check coolant flow valves for correct operation and settings HEATING NATURAL GAS 1 Beforeturning on the main electrical power switch besurethat all gas supply lines have been purged of air 2 Turn gas valve to ON position 3 Turn main electrical power switch to ON and set the thermostat to call for
20. onomizer WAN SYSTEMS Power Exhaust Options IMPORTANT A WARNING The Clean Air Act of 1990 bans the Improper installation adjustment alteration intentional venting of refrigerant CFC s and service or maintenance can cause property HCFC s as of July 1 1992 Approved damage personal injury or loss of life methods of recovery recycling or reclaiming Installation and service must be performed must be followed Fines and or incarceration by a qualified installer service agency may be levied for non compliance orthe gas supplier Owner should pay particular attention to the words NOTE CAUTION AND WARNING NOTES are intended to darify or make the installation easier CAUTIONS are given to prevent equipment damage WARNINGS aregiventoalert owner that personal injury and or equipment damage may result if installation procedure is not handled properly It is the intent of AAON Inc to provide accurate and current specification information However in the interest of product improvement AAON Inc reserves the right to change pricing specifications and or design of it s products without notice obligation or liablity 2003 AAON Inc all rights reserved throughout the world AAON amp AAONAIRE are registered trademarks of AAON Inc Tulsa OK 2 R15700 7 03 OWNER S INFORMATION Hectric shock hazard Can cause injury or death Before attempting to perform any service or maintenance tum the electrical p
21. ower to unit to OFF at disconnect switc h es Unit may have multiple power supplies AIRFLOW IS TO BE ADJ USTED AFTER INSTALLATION TO OBTAIN AN AIR TEMPERATURE RISE WITHIN THE RANGE SPECIFIED ON THE RATING PLATE DUE OB SPECIFICATION REVISIONS IT MAY BE NECESSARY TO ADJUST OR CHANGE THE SHEAVE OR PULLEY TO OBTAIN THE DESIRED AIRFLOW AT THE TIME OF INSTALLATION STARFUP TECHNICIAN MUSTC HEC K BLOWER MOTORAMPERAGETO ENSURE THAT THE AMPERAGE LISTED ON THE MOTOR NAMEPLATE ISNOTEXC EEDED CAUTION While the following incorrect operations may not cause damage to the system they will impair the performance and may cause the built in safety devices to cut the system off completely 1 LOW AMBIENT OPERATION The cooling section of a direct expansion DX unit will not operate properly when the outdoor tempera ture is below 55 F Outside air intake options are necessary if operation below 55 F is expected 2 MULTIPLE UNIT OPERATION When several units are used in conditioning the space and any are combination heating cooling units all system thermostat switches must beset at either heating cooling or set at off Do not run part of a system switched to an opposite mode Cooling only units should be switched to off at the thermostat during the heating season WIRING DIAGRAMS A complete set of unit specific wiring diagrams in both ladder and point to point form are laminated in plastic and located inside the
22. rain is shut down by a main limit located in the heat exchanger area or by an auxiliary limit mounted in the supply air fan housing 2 LP Propane Gas The sequence for LP Gas is the same as above but upon non proof of burner the gas train will enter a 10096 lockout condition 3 Electric When the thermostat calls for heat W1 makes R to the heat relay HR All N O contacts close and all N C contacts open Theheat relay makes R tothe first stage of electric heat On a fault condition the main limit located in the supply air or the auxiliary limit located in thesupply air fan housing will remove power from all contactors If additional heating is required a second set of elements can be turned on by W2 OPTIONAL When available the electric heat can be sequenced to provide a constant discharge air tempera ture 4 Steam or Hot Water This option adds a steam coil down stream of the cooling coil if supplied Connections and controls are provided by others SEQUENCE OF OPERATIONS Continued POWEREXHAUST w FULL MODULATINGECON In the unit OFF or in the minimum economizer position the power exhaust is off As the economizer begins to modulate open an end switch adjustable closes which starts the power exhaust fan motor The power exhaust operates until the economizer modulates below the end switch setting or the unit is shut off POWER EXHAUST w FULL MODULATING ECON WITH BUILDING PRESSURE CONTROL Intheunit
23. s will givethecrankcase heater ti meto dear liquid accumulation out of the compressor beforeit is required to run Always control the system from the thermostat or con trol panel never at the main power supply except in an emergency or complete shutdown of the system Duringthe cooling season if the air flow is reduced due to dirty air filters or other reasons the cooling coils will get too cold and result in excessiveliquid return tothe compressor As the liquid concentration accumulates oil iswashed out of the compressor leavingit starved for lubrication The compressors must be on a minimum of 4 minutes and off for a minimum of 5 minutes The cycle rate must not exceed 8 starts per hour THE COMPRESSOR LIFE WILL BE SERIOUSLY SHORTENED BY RESULTINGREDUCEDLUBRICA TION AND THE PUMPING OF EXCESS AMOUNTS OF LIQUID OIL AND REFRIGERANT GAS OR ELECTRIC HEATING Thesystem is designed toheat a given amount of air each minuteit operates Iftheamount of air heatedis greatly reduced approximately 1 3 capacity the heat ex changer heater coil temperature will increase above acceptable level and result in shut down by a high temperature safety switch incorporated either in the heat exchanger or the heater area GAS HEAT UNITS WARNING If duetosafety switch shut off or gas supply shut off failure ALWAYS CLOSE MANUAL GAS VALVE TO UNIT PRIOR TO ANY ELECTRICAL SERVICE PROLONGED OVERHEATING OF THE HEAT EXCHANGER WILL SHORTEN IT
24. stment Main orifice blocked Defective Ignition Control Refer to cooling trouble shooting page 10 1 2 WNE Ui 130 6 1 Ui 130 APUN APUNE 5 6 1 2 SY SITEMIORE EVAPORATOR MOTOR WILL NOT RUN BLOWER DOESN T DELIVER AIR BLOWER COMES ON BUT LITTLE OR HEAT SYSTEM OFF BURNER WON T COME ON COMBUSTION AIR BLOWER WON T RUN BURNER GOES OFF ON HIGH LIMIT IGNITION ON BURNER WON T LIGHT SUPPLY FAN BLOWER WON T RUN SERVICING Continued POSSIBLE CAUSE TROUBLE STEAM AND HOT WATER HEATING Check power at line side of contactor s 2 Thermostat not set for heating Overload relay tripped Heater Relay not energized Blower Contactor not energized Blower running backwards Dirty air filters Dirty coils Duct obstruction Belts loose if applicable Check steam traps valves and steam or hot water supply in accordance with manufactures instructions 1 UD 2 Faulty thermostat SYSTEM OFF BLOWER MOTOR WILL NOT RUN BLOWER DOESN T DELIVER AIR BLOWER COMES ON BUT LITTLE OR NO HEAT COOLING PACKAGE and UNITS with REMOTE CONDENSERS Check power at lineside of contactor s Thermostat not set for cooling High pressure control tripped Low pressure switch open loss of charge Overload thermal protector open in motor REFER TO MFG S INST
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