temperatures of the suction and discharge lines

[VIXS]

HI There All

Can anybody please confirm that the suction tempreature on a R22 and R407c system should be between 0 and 5 deg c.
The discharge around 60 and 70 deg c.
If i am not mistaken this is a more acurate way of working out if the system is low on refrigerant bearing in mind that there is no hot gas bypass and the expansion valve is working correctly and giving you a superheat of +-5 deg c

Victor

[Brian_UK]

Sounds reasonable, after all you are not trying to freeze anything only cool the air.

[puddleboy3]

I might be wrong but my general rule of thumb is you should not have any lower than 7 degrees C going back to your compressor. So if R22 with a suction pressure of about 60 psi(g) and a suction pipe temp of 7 degrees C would be 7 degrees superheat. Ideal

[US Iceman]

Hi VIXS,

Welcome to the RE forum.

I also think it is important to understand the relevance of the discharge temperature and discharge superheat as a function of the suction superheat.

Please also bear in mind the different refrigerants will have a different specific heat ratio for each refrigerant.

A refrigerant with a high specific heat ratio will produce a higher discharge temperature than a refrigerant with a lower specific heat ratio at the same operating conditions.

Suction superheat is only one measure of a systems' performance, which might not be dependent on refrigerant charge alone.

[puddleboy3]

Suction superheat is only one measure of a systems' performance, which might not be dependent on refrigerant charge alone.

I agree US Iceman, by measuring the suction superheat you are only confirming that the evaporator is performing correctly.