Lennox International Inc 2SCU13 Start-Up, Refrigerant Charge Adjustment, Refrigerant Charging

START-UP

CAUTION

If unit is equipped with a crankcase heater, it should be energized 24 hours before unit start-up to prevent compressor damage as a result of slugging.

1.Rotate fan to check for frozen bearings or binding.

2.Inspect all factory and field-installed wiring for loose connections.

3.After evacuation is complete, open liquid line and suction line service valves to release refrigerant charge (contained in outdoor unit) into system.

4.Replace the stem caps and secure finger tight, then tighten an additional 1/6 of a turn.

5.Check voltage supply at the disconnect switch. The voltage must be within the range listed on the unit nameplate. If not, do not start equipment until the power company has been consulted and the voltage condition corrected.

6.Set thermostat for cooling demand, turn on power to indoor blower and close the outdoor unit disconnect switch to start the unit.

7.Recheck unit voltage with unit running. Power must be within range shown on unit nameplate.

Refrigerant Charging

Units are factory charged with the amount of HCFC-22 refrigerant indicated on the unit rating plate. This charge is based on a matching indoor coil and outdoor coil with 15' line set. For varying lengths of line set, refer to Table 5 for refrigerant charge adjustment.

Refrigerant Charge Adjustment

Liquid Line Set	Oz. per 5 ft. adjust
Diameter	from 15 ft. line set*
3/8 in.	3 oz. per 5 ft.

*If line length is greater than 15 ft., add this amount. If line length is less than 15 ft., remove this amount.

Table 5

If the system is void of refrigerant, clean the system using the procedure described below.

1.Use dry nitrogen to pressurize the system and check for leaks. Repair leaks, if possible.

2.Evacuate the system to remove as much of the moisture as possible.

3.Use dry nitrogen to break the vacuum.

4.Evacuate the system again.

5.Weigh the appropriate amount of HCFC-22 refrigerant (listed on unit nameplate) into the system.

6.Monitor the system to determine the amount of moisture remaining in the oil. Use a test kit to verify that the moisture content is within the kit’s dry color range. It may be necessary to replace the filter drier several times to achieve the required dryness level. If system dryness is not verified, the compressor will fail in the future.

The outdoor unit should be charged during warm weather. However, applications arise in which charging must occur in the colder months. The method of charging is deter- mined by the unit’s refrigerant metering device and the outdoor ambient temperature.

Measure the liquid line temperature and the outdoor ambient temperature as outlined below:

1.Connect the manifold gauge set to the service valve ports as follows:

•Low pressure gauge to suction line service valve

•High pressure gauge to liquid line service valve

2.Close manifold gauge set valves. Connect the center manifold hose to an upright cylinder of HCFC-22.

3.If room temperature is below 70°F, set the room thermo- stat to call for heat. This will create the necessary load for properly charging the system in the cooling cycle.

4.Use a digital thermometer to record the outdoor ambient temperature.

5.When the heating demand has been satisfied, switch the thermostat to cooling mode with a set point of 68°F. When pressures have stabilized, use a digital thermometer to record the liquid and suction line temperatures.

6.The outdoor temperature will determine which charg- ing method to use. Proceed with the appropriate charging method.

Page 10 # 48283B006