T h e Q u a l i t y L e a d e r i n C o n d i t i o n i n g A i r
Refrigeration Installation
Turn service valves full out CCW (see Table 5) and then turn back in
PARTIAL CHARGE METHOD - Open service valve fully counterclockwise and then turn back in
“FINAL EVALUATION.”
FINAL EVALUATION
R e s i d e n t i a l S p l i t - 6 0 H z R 2 2 & R 4 1 0 A
R e v. : 5 J u n e , 2 0 0 8
does not perform to specifications the cooling TXV (air coil side) may need to be readjusted (if possible) until the cooling superheat values are met.
Checking Superheat and Subcooling
Determining Superheat:
1.Measure the temperature of the suction line at a point near the expansion valve bulb.
2.Determine the suction pressure by attaching refrigeration gauges to the suction schrader connection at the compressor.
3.Convert the pressure obtained in step 2 to saturation temperature (boiling point) by using the pressure/ temperature conversion table on the gauge set.
4.Subtract the temperature obtained in step 3 from step
1. The difference will be the superheat of the unit or the total number of degrees above saturation temperature. Refer to Tables 14a to 15 for superheat ranges at specific entering water conditions.
Example (R-22 refrigerant):
The temperature of the suction line at the sensing bulb is 50°F. The suction pressure at the compressor is 65 psig which is equivalent to 38°F saturation temperature from the
38°F subtracted from 50°F = 12°F Superheat.
Determining Sub-Cooling:
1.Measure the temperature of the liquid line on the smaller refrigerant line (liquid line) just outside of the cabinet. This location will be adequate for measurement in both modes unless a significant temperature drop in the liquid line is anticipated.
2.Determine the condensor pressure (high side) by attaching refrigerant gauges to the schrader connection on the liquid line service valve. If the hot gas discharge line of the compressor is used, refer to the appropriate column in Tables 14a to 15.
3.Convert the pressure obtained in step 2 to the saturation temperature by using the press/temp conversion table on the gauge set.
4.Subtract the temperature of Step 3 from the temperature of Step 1. The difference will be the
Example
The condenser pressure at the service port is 225 psig, which is equivalent to 110°F saturation temperature. Discharge pressure is 236 psig at the compressor (113°F saturation temperature). Measured liquid line temperature is 100°F. 100°F subtracted from 110°F = 10 degrees sub- cooling (13 degrees if using the compressor discharge pressure).
w w w. h e a t c o n t o l l e r. c o m | 21 |