Originally posted by thewoodman
I have an ongoing argument with my boss about reading the gauges. I say the green scale for R22 tells me the saturation temp. of the refrigerant. He says it is the actual temperature of the freon in the suction line. I say no it is the temperature at which the freon saturates at the corresponding pressure. Pressure temperature relationship. Ok.. he tells me he as two years of AC college and I can't convince him different. He still maintains it is the temperature of the freon. AM I not understanding this or what??

Like most, your "boss" attended school but either missed the point or was taught by an "experienced" instructor who de-emphasized such topics in the interests of being "practical".

Unless you are deriving compression ratio or setting pressure controls accurately then the only useful information on the gauge is the sat temp (even more true when you work with several refrigerants).

Most of the heat absorbed in the evaporator, and rejected in the condenser are latent exchanges so the respective sat temp represents the temp at witch the refrigerant is exchanging heat. This is mucho impport-o.

I do get pissed every time someone makes reference to head or suction pressure because they are missing this major point. The top techs out there will not flame this thread and they are all nodding right now.

<snip>
He says it is the actual temperature of the freon in the suction line.
</snip>
1. Because of what I said, it is very close to the actual temp of the refrigerant at saturation *inside the evap coil* before super heating occurs.
2. If it was the actual temperature of the freon **in the suction line**, this would only be true if the saturation point extended out side the evaporator (i.e. liquid flood back) and into the suction line which is bad ju ju.

If the state exams where worth a crap your "boss" would not have the license and perhaps you would (other real qualifications permitting). You could then bust him down to installer until he learned something (two years of AC college notwithstanding).

I have not fully discussed the subject here. It is also possible that your "boss" understands it better than your question indicated but has failed to communicate the distinction between suction line and evaporator.

BTW, the P-H chart never lies.

[Edited by mdman on 06-11-2005 at 02:14 PM]