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1. Hot gas from compressor flows through the reversing (4-way)

valve and is directed to the indoor coil header. At the header
refrigerant is directed to the indoor coil where it is condensed
and subcooled and then exits through the indoor coil check
valve to the liquid line. (The TXVs stop the refrigerant flow dur-
ing the heating cycle.)

2. The refrigerant then feeds the outdoor coil by way of filter-drier,

a distribution manifold, and then through capillary tubes on
each circuit.

3. Each circuit evaporates the refrigerant and all the circuits are

combined in the outdoor header (with some of the circuits flow-
ing through the check valve “A”).

4. The refrigerant then flows through the reversing (4-way) valve,

accumulator and back to the compressor.

LEGEND

NOTES:

1. Check valves are designated “A” through “D.”
2. Illustrations are typical and do not portray exact coil circuiting.

3. Check valve positions:

open, 

 closed.

TXV —

Thermostatic Expansion Valve

Fig. 17 — Typical Heat Pump Heating Operation Schematic

(38AQS012 Shown)

Summary of Contents for 38AQS012

Page 1: ...her handy Use care in handling rigging and setting bulky equipment INSTALLATION Step 1 Complete Pre Installation Checks UNCRATE UNIT Remove unit packaging except for the top skid assembly which should be left in place until after the unit is rigged into position INSPECT SHIPMENT File claim with shipping company if shipment is damaged or incomplete CONSIDER SYSTEM REQUIREMENTS Consult local buildin...

Page 2: ...HPS Cutout psig Cut in psig Loss of Charge Switch Liquid Line Cutout psig Cut in psig Head Pressure No 2 Fan Cycling Opens psig Closes psig Oil Pressure Switch Differential Set Point psig Close on Rise Open on Fall Defrost Pressure Switch HPS2 Opens psig Closes psig 400 300 7 3 22 5 160 10 255 10 9 5 1 5 280 10 180 2 THERMOSTAT Defrost Switch Opens F Closes F 65 27 80 27 UNIT 38AQS 012 016 OPERATI...

Page 3: ...ns NOTES 1 Service clearances are as follows Side compressor 31 2 ft 1067 mm Side opposite compressor 3 ft 914 mm Ends 2 ft 616 mm Top 5 ft 1524 mm 2 See Table 2 and Fig 3 for weight distribution and center of gravity ...

Page 4: ...r Fan Relay 14 Control Relay CR3 24 Muffler 6 Outdoor Fan Contactor 15 Liquid Line Solenoid 25 Oil Solenoid 7 Compressor Contactor 16 Control Relay CR2 26 Reversing Valve 8 Fan Motor Capacitors 17 No Dump Relay NDR 27 Accumulator 9 Circuit Breaker 18 Oil Pressure Switch 28 Coil 10 Fan No 2 19 Fusible Plug hidden 2 1 4 3 38AQS012 016 38 1 4 972 mm 26 11 16 678 mm Fig 3 Weight Distribution Table 2 W...

Page 5: ...s field supplied Weight distribution shown in Fig 3 and Table 2 deter mines the type of support required Bolt unit securely to pad or supports after unit is in position and is level Be sure to mount unit level to ensure proper oil return to compressors Mounting holes on unit can be used to secure unit to vibration isolators if required COMPRESSOR MOUNTING As shipped compressor is held down by 4 bo...

Page 6: ...ator between the filter drier s and the liquid connections on the indoor 40RMQ unit Braze or silver alloy solder all connections Pass nitrogen or other inert gas through piping while making connections to prevent formation of copper oxide Copper oxides are extremely active under high temperature and pressure Failure to prevent collection of copper oxides may result in system component failures VAP...

Page 7: ... details 2 All wiring must comply with applicable local and national codes 3 Wiring and piping shown are general points of connection guides only and are not intended for or to include all details for a specific installation 4 Filter driers must be bi flow type suited for heat pump duty 5 Internal factory supplied TXVs and check valves not shown Fig 5A Typical System Piping and Wiring 38AQS With 4...

Page 8: ...xpansion Valve Piping NOTES 1 All piping must follow standard refrigerant piping techniques Refer to Carrier System Design Manual for details 2 All wiring must comply with applicable local and national codes 3 Wiring and piping shown are general points of connection guides only and are not intended for or to include all details for a specific installation 4 Filter driers must be bi flow type suite...

Page 9: ...um outdoor ambient air temperature for full cooling capacity Table 6 Minimum Outdoor Air Operating Temperature Applies to Cooling mode of operation only UNIT 38AQS COMPRESSOR CAPACITY CONDENSER TEMP F C MINIMUM OUTDOOR TEMP F C Standard Unit 012 100 67 90 32 2 80 26 7 35 1 7 45 7 2 016 100 67 90 32 2 80 26 7 23 5 36 2 2 LIQUID LINE BI FLOW FILTER DRIER TXV REDUCING TEE INDOOR COIL B A A UNIT 38AQS...

Page 10: ...onged peri od it is recommended that the suction and discharge valves be closed to prevent an excessive accumulation of refrigerant in the compressor oil 3 Terminals for field power supply are suitable for copper copper clad aluminum or aluminum conductors CONTROL CIRCUIT WIRING Unit internal control cir cuit voltage is 24 volts See Table 8 for recommended thermo stats Connect thermostat assembly ...

Page 11: ... National Electric Code U S A Standard Article 440 2 Motor RLA and FLA values are established in accordance with UL Underwriters Laboratories Standard 1995 U S A Standard Table 8 Recommended Thermostats LEGEND Thermostat kit includes Temp System relay pack Subbase has ON AUTO fan switch IMPORTANT The common COM terminals from all three fan coil relay boards must be connected to the P terminal in c...

Page 12: ...Ground NEC National Electrical Code U S A TB Terminal Block Field Wiring Factory Wiring Fig 9 Main Power Supply Wiring LEGEND EQUIP Equipment GND Ground HC Heater Contactor IFC Indoor Fan Contactor IFM Indoor Fan Motor NEC National Electrical Code U S A TB Terminal Block Fig 10A Field Wiring Diagram 38AQS012 or 016 System With Standard Thermostat and Electric Heat ...

Page 13: ...UPPLY 3 Ph ONLY L1 L2 L3 EQUIP GND TB1 HC1 HC1 CIRCUIT BREAKER 5 HP AND LARGER UNIT WIRING IFM BLK BLK BLK 21 22 23 12 13 11 1 2 3 HTR1 IFC FAN COIL NO 1 RELAY BOARD 33ZCRLYBRD FAN COIL NO 2 RELAY BOARD 33ZCRLYBRD FAN COIL NO 3 RELAY BOARD 33ZCRLYBRD TSTAT LEGEND NOTE Use copper conductors only EQUIP Equipment GND Ground HC Heating Contactor HTR Electric Heater IFC Indoor Fan Contactor IFM Indoor ...

Page 14: ...LY 3 Ph ONLY L1 L2 L3 EQUIP GND TB1 HC1 HC1 CIRCUIT BREAKER 5 HP AND LARGER UNIT WIRING IFM BLK BLK BLK 21 22 23 12 13 11 1 2 3 HTR1 IFC FAN COIL NO 1 RELAY BOARD 33ZCRLYBRD FAN COIL NO 2 RELAY BOARD 33ZCRLYBRD FAN COIL NO 3 RELAY BOARD 33ZCRLYBRD TSTAT LEGEND NOTE Use copper conductors only EQUIP Equipment GND Ground HC Heating Contactor HTR Electric Heater IFC Indoor Fan Contactor IFM Indoor Fan...

Page 15: ...ING THERMOSTAT HH07AT172 Degrees F and HH07AT162 Degrees C The thermostat has an adjustable heat anticipator for both first and second stage heating circuits SETTINGS Set adjustment lever for first stage anticipator at 0 79 left hand side Set adjustment lever for second stage anticipator right hand side at 0 42 OUTDOOR THERMOSTAT Refer to 40RMQ accessory heater installation instructions for detail...

Page 16: ...arge modifications should be done only under supervision of a qualified refrigeration mechanic With all fans operating and compressor operating fully loaded adjust the refrigerant charge in accordance with the unit charging charts located on the inside of the control box doors and in Fig 12 and 13 1 Be sure to use Refrigerant 22 2 Regulate refrigerant drum valve to maintain suction pres sure at 80...

Page 17: ...TC 1 closes condensing unit A and condensing unit B will start with unloaded compressors When TC 2 closes the compressors in both con densing units will load Heating When TH 1 closes both condensing unit A and condensing unit B will start in the Heating mode When TH 2 closes the auxiliary heat electric resistance heat will be energized SAFETIES The high pressure switch loss of charge switch oil pr...

Page 18: ...r Unit Fans Each fan is supported by a formed wire mount bolted to the fan deck and covered with a wire guard The exposed end of the motor shaft is covered with a rubber boot In case a fan motor must be repaired or replaced be sure the rubber boot is put back on when the fan is rein stalled and be sure the fan guard is in place before starting the unit Figure14 shows the proper position of the mou...

Page 19: ...mmended coil cleaners is strongly discouraged since coil and unit durability could be affected The following field supplied equipment is required for coil cleaning 2 1 2 gallon garden sprayer water rinse with low velocity spray nozzle Totaline Environmentally Sound Coil Cleaner Application Instructions Perform the following procedure to clean the coil NOTE Wear proper eye protection such as safety...

Page 20: ...20 TROUBLESHOOTING CHART HEATING CYCLE LEGEND NOTE See Fig 17 for diagram showing heating cycle operation CCH Crankcase Heater N C Normally Closed ...

Page 21: ...21 TROUBLESHOOTING CHART COOLING CYCLE LEGEND NOTE See Fig 18 for diagram showing heating cycle operation CCH Crankcase Heater TXV Thermostatic Expansion Valve ...

Page 22: ...drier a distribution manifold and then through capillary tubes on each circuit 3 Each circuit evaporates the refrigerant and all the circuits are combined in the outdoor header with some of the circuits flow ing through the check valve A 4 The refrigerant then flows through the reversing 4 way valve accumulator and back to the compressor LEGEND NOTES 1 Check valves are designated A through D 2 Ill...

Page 23: ...valve A and is then redirected to a final subcooling pass in center of coil face 012 or exits header via outlet tube 016 5 Refrigerant leaves the outdoor coil by way of check valve B to the liquid line 6 The refrigerant then flows through the filter drier and feeds the indoor coil by way of the TXV and feeder valves 7 Each circuit evaporates the refrigerant and the circuits are com bined in the in...

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Page 26: ...nue or change at any time specifications or designs without notice and without incurring obligations PC 111 Catalog No 533 80001 Printed in U S A Form 38AQS 9SI Pg 26 1 01 Replaces 38AQS 8SI Book 1 1 Tab 5a 5a Copyright 2001 Carrier Corporation ...

Page 27: ...IRING TERMINALS including main power supply TIGHT Y N _____________ HAS CRANKCASE HEATER BEEN ENERGIZED FOR 24 HOURS Y N _____________ INDOOR UNIT HAS WATER BEEN PLACED IN DRAIN PAN TO CONFIRM PROPER DRAINAGE Y N ___________ ARE PROPER AIR FILTERS IN PLACE Y N ____________ HAVE FAN AND MOTOR PULLEYS BEEN CHECKED FOR PROPER ALIGNMENT Y N ___________ DO THE FAN BELTS HAVE PROPER TENSION Y N ________...

Page 28: ...COMPRESSOR AMPS L1 L2 L3 ______ ______ ______ ______ ______ _______ CHECK THE COMPRESSOR OIL LEVEL SIGHT GLASSES ARE THE SIGHT GLASSES SHOWING OIL LEVEL IN VIEW Y N NOTES ___________________________________________________________________________________________________ ___________________________________________________________________________________________________ _____________________________...

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