Trane PTAC-SVX01C-EN manual Maintenance Cooling Performance Test, Thermometers, Sling Psychrometer

Maintenance

Cooling Performance Test

Thermometers

The following precautions are necessary in observing the thermometer readings in the cooling performance test.

1.Use two accurately calibrated refrigeration type thermometers or a thermocouple potentiometer.

2.Thermometers are affected by body heat or changes in airflow. Therefore, secure the thermometers in proper locations with masking tape, wire, or other applicable retainers.

3.Observe readings without touching or moving the thermometers.

Sling Psychrometer

Use a sling psychrometer to obtain the wet-bulb temperature and determine the percent relative humidity.

To obtain the wet-bulb, follow this procedure using the sling psychrometer.

•Saturate the wick (only once during procedure of obtaining wet-bulb readings) with clean water slightly below room temperature.

•Obtain the psychrometer reading five to six feet in front of the unit and approximately four feet off the floor.

Note: Direct discharge airflow away from the sling psychrometer.

Do not perform the cooling performance test when the outside temperature is 20°F below the room temperature. For best results, perform the test under peak load conditions.

The air conditioner must operate at least 20 minutes on the HIGH COOL position before testing.

Cooling Performance Test

Record the following temperatures for the cooling performance test:

•Dry-bulb temperature of return air at conditioner. Locate thermometer as illustrated on previous page.

•Dry-bulb temperature of discharge air. Locate the thermometer as illustrated on previous page.

•The dry-bulb thermometer temperature on the sling psychrometer should be plus or minus 1°F within reading obtained on thermometer in the return air. Check wet-bulb temperature on sling psychrometer and record same.

•After recording the wet-bulb temperature, dry- bulb temperature, and return air temperature, calculate the temperature difference as follows.

•Subtract temperature obtained in Step B from temperature obtained in Step A. Use the remainder temperature to calculate from the cooling change of temperature in the Maintenance general information section.

Example: Assume a PTHE1501 unit is under test and the temperature readings indicated below were obtained.

1.Return air dry-bulb temperature: 80°F, Step A.

2.Discharge air dry-bulb temperature: 69°F, Step B.

3.Return air, wet and dry-bulb temperature as recorded in Step C: dry- bulb 80°F, wet-bulb 75°F.

4.In left hand column of cooling capacity charge headed dry-bulb, find the 80° value in Table 20, p. 25.

5.In column headed wet-bulb find the 75° value and find the value "8 -13" in the cooling range column under model “PTHE1501”.

This data shows the temperature of the air passing through the cooling coil is reduced at least 8°F but not more than 13°F. This example unit is operating normally for the existing conditions.

For the example unit under test, the temperature difference was 11°F (80°F, return air, minimum 69°F discharge air). Because the value is within the listed cooling range 8 - 13, this unit is considered to be operating normally.

Note: Never test operation without the unit in the wall sleeve. A serious change in design specifications for air movement through the evaporator and condenser compartments, causing the fan motor to over heat and the refrigeration system to become unbalanced will occur when the unit is not installed in the wall sleeve.

Electric Heat Test

For the electric heat test, the following readings must be recorded after the unit is interconnected with a wattmeter or by recording the total amp draw to the unit.

Note: The cabinet front must be in place during this test.

•Record supply voltage to unit.

•Operate unit in highest heat setting.

•Record wattage recorded on wattmeter or total amp draw to unit.

•Refer to the electric heat capacity and electrical data section (whichever is applicable for voltage rating on the unit being tested.)

•The total watts or amps recorded should fall with in the minimum and maximum watts/amps listed on these charts

Example: Assume that a PTHE1501 230/208V with 3.5 kW electric heater is under test.

1.Supply voltage as recorded - 208V.

2.Watts recorded -2750W or amps recorded - 13.5 amps.

PTAC-SVX01C-EN 35