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
Turn service valves full out CCW (see Table 5) and then turn back in
of hunting in TXV systems. This increase in subcooling will require 5 minutes or so of operation before it should be measured. After values are measured, compare to the chart and go to “FINAL EVALUATION.”
PARTIAL CHARGE METHOD - Open service valve fully counterclockwise and then turn back in
to the suction port at a rate not to exceed five pounds [2.27 kg] per minute. Keep adding refrigerant until the complete charge has been entered. Superheat is measured using suction temperature and pressure at the compressor suction line. Subcooling should be measured using the liquid line temperature immediately outside the compressor section cabinet and either the liquid line service valve pressure or the compressor discharge pressure. Note that different values from tables 14a to 15 will be obtained due to the pressure losses through the condenser heat exchanger. Adding refrigerant will increase
FINAL EVALUATION
-In a split system, cooling subcooling values can be misleading depending on the location of the measurement. Therefore, it is recommended that charging be monitored in the heating mode. Charge should be evaluated by monitoring the subcooling in the heating mode. After initial check of heating
R e s i d e n t i a l S p l i t - 6 0 H z R 4 1 0 A
R e v. : 0 3 A u g u s t , 2 0 1 2
Refrigeration Installation
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.
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
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