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CSRA-SVX02A-EN
System Start-Up
Environmental scientists have found evidence that refrigerant emissions
contribute to depletion of ozone in the upper atmosphere and can increase
global warming. Trane encourages every effort to eliminate, if possible, or
vigorously reduce the emission of CFC, HCFC and HFC refrigerant to the
atmosphere that can result from installation, operation, routine maintenance,
or major service on this equipment. Only technicians with EPA certification
should be allowed to handle CFC, HCFC or HFC refrigerants. Compliance or
certification to other local or state codes may also be required when handling
refrigerants. Always act in a responsible manner to conserve refrigerants.
Refer to general service bulletin MSCU-SB-1 (latest edition).
Subcooling
With the unit operating at "Full Circuit Capacity", acceptable subcooling
ranges between 14°F to 22°F.
Measuring Subcooling
A. At the liquid line service valve, measure the liquid line pressure. Using a
Refrigerant 22 pressure / temperature chart, convert the pressure reading
into the corresponding saturated temperature.
B. Measure the actual liquid line temperature as close to the liquid line service
valve as possible. To ensure an accurate reading, clean the line thoroughly
where the temperature sensor will be attached. After securing the sensor
to the line, insulate the sensor and line to isolate it from the ambient air.
Note: Glass thermometers do not have sufficient contact area to give an
accurate reading.
C. Determine the system subcooling by subtracting the actual liquid line tem-
perature (measured in b) from the saturated liquid temperature (converted
in a).
Superheat
The reliability and performance of the refrigeration system is heavily
dependent upon proper expansion valve adjustment. Therefore, the
importance of maintaining the proper superheat cannot be over emphasized.
Accurate measurements of superheat will provide the following information.
A. How well the expansion valve is controlling the refrigerant flow.
B. The efficiency of the evaporator.
C. The amount of protection the compressor is receiving against flooding or
overheating.
The recommended range for superheat is 10 to 16 degrees at the
evaporator.
Systems operating with less than 10 degrees of superheat:
A. Could cause serious compressor damage due to refrigerant floodback.
B. Removes working surface from the evaporator normally used for heat
transfer.
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