Fedders CH18ABD1 Model, SUB-COOLING Charging, Final Checks for Installer, Cooling Operation

Model

SUB-COOLING CHARGING

For proper sub-cooling readings, a standard high side gauge is required for pressure readings.

Use the charts below to determine the required sub-cooling value.

INSTRUCTIONS

1.Measure the outdoor air temperature. (T1)

2.Measure the liquid line pressure and determine the liquid refrigerant temperature by the scale on the high side pressure gauge. (T2) In cooling mode take reading at the indoor coil before TXV. In heating mode take reading at the liquid line service valve on outdoor unit.

3.Measure the liquid line temperature on the liquid line. (T3) In cooling mode take reading at the indoor coil before TXV. In heating mode take reading at the liquid line service valve on outdoor unit.

4.Subtract T3 from T2. (T2 – T3) This is the subcooling value. Compare this value and the outdoor temperature (T1), to the charts below. If the value is below the line, add refrigerant. If the value is above the line, remove refrigerant charge. When removing refrigerant, always use standard reclaim procedures.

Adjusting TXV

For the majority of installations no adjustment to the TXV setting is required. However, if the measured superheat at the indoor coil is less than 4° or greater than 8° an adjustment is required. The adjustment stem is at the base of the valve under the flare nut. To increase superheat, tighten the stem clockwise and to decrease superheat, back-out the stem counter- clockwise. Use a 1/4” refrigeration service wrench for this function.

119SUB-COOLING CHARTS FOR UNITS WITH TXV

COOLING MODE

12

-T3)
(T2	10
SUBCOOLING	8

6

4

°F	°F	°F	°F	°F	°F
	OUTDOOR TEMPERATURE			°F (T1)

HEATING MODE

37

T3)-	35
(T2	33
	31
SUBCOOLING
	29

27

25

23

21

OUTDOOR TEMPERATURE °F (T1)

All values are for reference only and may vary up or down. All heating values are with frost-free outdoor coil. When the outdoor temperature is below 40°F manually defrost the unit before reading.

5

FINAL CHECKS FOR INSTALLER

1.Ensure that all wiring is routed away from tubing and sheet metal edges to prevent rub-through or wire pinching.

2.Ensure that all wiring and tubing is secure in unit before adding panels and covers.

3.Tighten service valve stem caps to 1/12 turn past finger tight.

4.Leave this manual with owner. Explain system operation and periodic maintenance requirements outlined in manual.

COOLING OPERATION

Turn the thermostat heat/cool switch to the cool position. Set the desired temperature on the thermostat dial. Do not operate the cooling unit for extended periods at indoor temperatures over 85°F. The unit indoor design temperature range is between 70°F and 80°F in the cooling mode.

It is not recommended to vary the temperature settings more than 5°F. Varying the temperature more than 5 degrees or turning the thermostat off for periods less than 12 hours can actually cost you more in energy consumption than keeping the temperature constant. Consider indoor plants and pets when varying the temperature from the normal comfort level.

HEATING OPERATION

Turn the thermostat heat/cool switch to the heat position. Set the desired temperature on the thermostat dial. Do not operate the heating unit at indoor temperatures over 80°F. The unit indoor design temperature range is between 65°F and 80°F in the heating mode.

Never operate the unit in the cooling mode at outdoor temperatures below 60°F without a low ambient control. Never operate the unit in the heating mode at outdoor temperatures above 70°F.

Auxiliary heat

Most heat pump installations include electric resistance heat for auxiliary heat (when the outdoor temperature is too low for the heat pump to provide enough heat) and for emergency heat (the outdoor unit is not working). On a properly-sized installation the heat pump will supply all the heat needed during cool weather. As the temperature drops, the heat output from the heat pump will be reduced. The auxiliary heat installed in the system will come on as needed to make up for this reduction of heat output.

The need for auxiliary heat is detected by the thermostat. If the thermostat senses a temperature fall of more than 2°F below the set point, the auxiliary heat will turn on. For this reason, setting the thermostat to the desired temperature and not changing the temperature during the day can be more economical than varying the thermostat setting.

If it is intended to set the temperature back at night, consider that, when the temperature is turned back up to the normal setting, the system will be operating during the coldest time of the day (early morning hours) and may require auxiliary heat if the increase in temperature is above 2°F.

Emergency heat

This switch will turn the outdoor unit off and use the electric auxiliary heat only to provide heat. If outdoor unit should malfunction, turn the emergency heat switch to the ON position and contact your service person.