background image

15

Heating Cycle

 

The heat pump operates in the heating cycle by redirecting 

refrigerant flow through the refrigerant circuit external to the 

compressor.  This is accomplished with the reversing valve.  

Hot discharge vapor from the compressor is directed to the 

indoor coil (evaporator on the cooling cycle) where the heat 

is removed, and the vapor condenses to liquid.

It then goes through the expansion device to the outdoor 

coil (condenser on the cooling cycle) where the liquid is 

evaporated, and the vapor goes to the compressor. 

 

When the solenoid valve coil is operated either from 

heating to cooling or vice versa, the piston in the reversing 

valve to the low pressure (high pressure) reverse positions 

in the reversing valve.  The following figure shows a 

schematic of the heat pump in the heating cycle. 

For Heat Pump units, the expansion devices are Fixed 

Thermal Expansion Devices (TXV) and perform the same 

function on the heating cycle as on the cooling cycle.  The 

Fixed TXV also act as check valves to allow for the reverse 

of refrigerant flow. 

When the heat pump is on the heating cycle, the outdoor 

coil is functioning as an evaporator. The temperature 

of the refrigerant in the outdoor coil must be below the 

temperature of the outdoor air in order to extract heat from 

the air. Thus, the greater the difference in the outdoor 

temperature and the outdoor coil temperature, the greater 

the heating capacity of the heat pump. This phenomenon 

is a characteristic of a heat pump. It is a good practice to 

provide supplementary heat for all heat pump installations 

in areas where the temperature drops below 45° F. It is 

also a good practice to provide sufficient supplementary 

heat to handle the entire heating requirement should 

there be a component failure of the heat pump, such as a 

compressor, or refrigerant leak, etc. 

Since the temperature of the liquid refrigerant in the 

outdoor coil on the heating cycle is generally below 

freezing point, frost forms on the surfaces of the outdoor 

coil under certain weather conditions of temperature and 

relative humidity.  Therefore, it is necessary to reverse the 

flow of the refrigerant to provide hot gas in the outdoor coil 

to melt the frost accumulation. This is accomplished by 

reversing the heat pump to the cooling cycle. At the same 

time, the outdoor fan stops to hasten the temperature 

rise of the outdoor coil and lessen the time required for 

defrosting. The indoor blower continues to run, and the 

supplementary heaters are energized. 

Defrost Control

During operation the power to the circuit board is controlled 

by a temperature sensor, which is clamped to a feeder tube 

entering the outdoor coil. Defrost timing periods of 30,60 

and 90 minutes may be selected by setting the circuit 

board jumper to 30, 60 and 90 respectively. Accumulation 

of time for the timing period selected starts when the 

sensor closes (approximately 30°± 5°F), and when the wall 

thermostat calls for heat. At the end of the timing period, 

the unit’s defrost cycle will be initiated provided the sensor 

remains closed. When the sensor opens (approximately 

60°± 5°F), the defrost cycle is terminated and the timing 

period is reset. If the defrost cycle is not terminated due to 

the sensor temperature, a twelve-minute override interrupts 

the unit’s defrost period. 

TROUBLESHOOTING

Suggested Field Testing/Troubleshooting

TESTING DEFROST CONTROL 

NOTE: PCBDM133 Defrost controls have a three 

(3) minute compressor off cycle delay.

 

NOTE: The PCBDM133 defrost controls are 

shipped from the factory with the compressor 

delay option selected. This will de-energize the 

compressor contactor for 30 seconds on defrost 

initiation and defrost termination. If the jumper 

is set to normal, the compressor will continue 

to run during defrost initiation and defrost 

termination. The control will also ignore the 

low-pressure switch connected to R-PS1 and 

PS2 for 5 minutes upon defrost initiation and 5 

minutes after defrost termination.

To check the defrost control for proper  

sequencing, proceed as follows: With power ON; 

 

unit not running. 

1.  Jumper defrost thermostat by placing a jumper wire 

across the terminals “DFT” and “R”/” R-DFT” at 

Summary of Contents for M Series

Page 1: ...N THIS MANUAL SHOULD SERVICE THE EQUIPMENT THE MANUFACTURER WILL NOT BE RESPONSIBLE FOR ANY INJURY OR PROPERTY DAMAGE ARISING FROM IMPROPER SERVICE OR SERVICE PROCEDURES IF YOU SERVICE THIS UNIT YOU A...

Page 2: ...MENT PARTS Ordering Parts When reporting shortages or damages or ordering repair parts give the complete unit model and serial numbers as stamped on the unit s nameplate Replacement parts for this app...

Page 3: ...ng or installing this unit Multiple power sources may be present Failure to do so may cause property damage personal injury or death WARNING To prevent the risk of property damage personal injury or d...

Page 4: ...ly within 5 days 4 File the claim with the following supporting documents a Original Bill of Lading certified copy or indemnity bond b Original paid freight bill or indemnity in lieu thereof c Origina...

Page 5: ...ses have holes under the outdoor coil to permit drainage of defrost water accumulation The unit must be situated to permit free unobstructed drainage of the defrost water and ice A minimum of 2 cleara...

Page 6: ...36 minimum clearance is required between the condenser coils Adequate clearance around the unit should be kept for safety service maintenance and proper unit operation A clearance of 48 is recommende...

Page 7: ...bserved when installing the unit Provisions for forks have been included in the unit base frame No other fork locations are approved Unit must be lifted by the four lifting holes located at the base f...

Page 8: ...is unit Multiple power sources may be present Failure to do so may cause property damage personal injury or death WARNING HIGH VOLTAGE To avoid personal injury or death due to electrical shock do not...

Page 9: ...t the power leads at the point of distribution in accordance with the unit data plate The unit must be electrically grounded in accordance with local codes or in the absence of local codes with the la...

Page 10: ...ever connecting thermostat wires to terminals on sub base DO NOT use larger than 18 AWG wire A transition to 18 AWG wire may be required before entering thermostat sub base NOTE Refer to unit wiring d...

Page 11: ...must first be performed in accordance with this manual Damage or repairs due to failure to comply with these requirements are not covered under the warranty After the machines are used for temporary h...

Page 12: ...airflow setting to be between 300 and 500 CFM per ton see Table below For models with electric heat the total airflow must not be less than that required for operation of the electric heaters See App...

Page 13: ...quid small line near liquid line access fitting with adequate contact and insulate for best possible reading 3 Check subcooling and superheat System should have a subcooling and superheat within the r...

Page 14: ...operation if outdoor ambient is mild If the outdoor ambient is low and the unit operates properly in the heating cycle you may check the pressure cutout operation by blocking off the indoor return air...

Page 15: ...surfaces of the outdoor coil under certain weather conditions of temperature and relative humidity Therefore it is necessary to reverse the flow of the refrigerant to provide hot gas in the outdoor co...

Page 16: ...for Electrical Failure 1 Place unit into the cooling mode Test for 24 volts at the solenoid If there is no voltage present at coil check the control voltage 2 If voltage is present loosen the nut on...

Page 17: ...be made at least every two months more often if necessary because of local conditions and usage Dirty throwaway filters should be discarded and replaced with a new clean filter Disposable return air f...

Page 18: ...18 Wiring Example Electric Heat Wiring Example...

Page 19: ...2080 939 0 74 0 4 2056 952 0 75 0 6 1973 1000 0 79 0 6 1967 1003 0 79 0 8 1887 1048 0 83 0 8 1890 1051 0 83 T3 0 2 2176 878 0 69 T3 0 2 2145 902 0 71 0 4 2080 939 0 74 0 4 2056 952 0 75 0 6 1973 1000...

Page 20: ...2 6 5 119 129 125 150 134 148 150 150 7 2 6 5 142 155 150 175 6 9 1 0 3 3 5 Direct Drive Standard Static 1 GPH1660M 208 230 1 60 1 26 9 152 9 EH 1S15 11 3 15 0 54 2 62 5 EH 1S20 15 0 20 0 72 2 83 3 EH...

Page 21: ...RB LOCATION EMBOSS FOR THRU THE BASE UTILITIES RETURN 11 X 25 SUPPLY 12 X 17 Horizontal Discharge Vertical Discharge NOTE Refer to IOD 7082 included in the literature pack for installing horizontal du...

Page 22: ...lectric Heater Heater Type X Staged S SCR modulating Voltage 1 208 230 1 60 Single phase 60 Hz Chassis S Small Kilowatt 5 5 kW 10 10 kW 15 15 kW 18 18 KW 20 20 kW 30 30 kW EH S05 5 1500 EH S10 10 1500...

Page 23: ...1 F1 BK RD 208 230V 1PH 60Hz L1 L2 T1 T2 C S CM BR RD GR BK GR RD FB3 F3 F3 5 BK RD RD YL BR BK PU BK RD PU BK 5 L1 L2 T1 T2 BK BC COMP RC COM H F PU PU CMC L1 L2 T1 T2 FB2 F2 F2 BK RD BK RD BK PU BR...

Page 24: ...LP Liquid Propane Residential Package Outdoor Section ELECTRICAL Supply Voltage Measure L1 and L2 Voltage L1 L2 Compressor Amps Condenser Fan Amps PRESSURES TEMPERATURES Suction Circuit Pressure Suct...

Page 25: ...25 THIS PAGE INTENTIONALLY LEFT BLANK...

Page 26: ...26 THIS PAGE INTENTIONALLY LEFT BLANK...

Page 27: ...27 THIS PAGE INTENTIONALLY LEFT BLANK...

Page 28: ...OODMAN BRAND AMANA BRAND GOODMAN BRAND AMANA BRAND PRODUCT REGISTRATION Thank you for your recent purchase Though not required to get the protection of the standard warranty registering your product i...

Reviews: