Heat Pump Pressure Valves

[MechGuy00]

I have a heat pump with hot gas bypass, water cooled here in Southern Georgia. The manufacturer's literature explains that the compressor has two high/low pressure switches respectively. The one is supposed to be set to 30 PSI, the other at 400PSI. Am I correct in suspecting that 30 PSI to extremely low? These units operate on R-22.

 

[ChasBean1]

Might be talking out of school as I'm not a refrigeration tech, but I have a table showing high/low side pressures for R22 of 211/144 (psig). So the high switch would be 189 above the high and low would be 114 below the low. Doesn't seem odd, but again, not my exact area..

 

[TheBlacksmith]

I'm more familar with the older R-12 systems from my shipboard days, but those pressures sound reasonable.

 

[chicopee]

For a heat pump the 30dF seems reasonable for your location. Dont forget on cold weather if the ambient temp is relatively, let's say 40df you want the refrigerant to be as low temp as possible so as to absorb enough ambient "heat" for the refrigerant to go from saturated vapor to slightly superheated before entering the compressor. At 30 psig, R22 has a saturation temperature of -10dF so there is a good amount of temperature differential for heat absorption on the low side.

At a certain low temperature the heat pump will generate insufficient heat and supplemental heat will be necessary, however, I don't know if this is the case where you live but where I reside in MA it will be necessary

 

[MintJulep]

30 psi for an R-22 low-pressure cut-out switch is reasonable. Maybe a little high.