How to measure superheat and subcooling

[Steve Wright]

US Iceman and Argus made very good points as to the importance of superheat and the measurement of.

I can added a couple of comments, if specific manufacture data not available some suggested settings are high temp 10-12*F SH, medium temp 6-8*F SH, low temp 4-6*F SH.

You must make sure that you have at least 20*F SH 6 inches from the compressor at all times to prevent flood back. You are also limited to a maximum return gas temp but that will vary based on several factors some are suction press, head press, refrigerant type, etc.

Return gas temps that are too high (high superheat at comp) will cause high discharge line temps that leads to oil failure then compressor failure.

You stated that you had Sporlan set valves, if you were not specific with your details to them they will need to be set in the field if they are adjustable.

You did not list it but I would monitor discharge line temp. It should generally not exceed 225*f on a reciprocating compressor for maximum life. The actual temps you will see are generally determined by high and low side pressures, refrigerant type, type of compressor, etc.
Steve Wright CM