Pressures and temperatures of a properly charged AC unit using R-22 that has a clean condenser should be about 76 PSIG and 45 degrees F on the low side, and, if it is a design day (usually assumed to be 95 degrees F), the high side maybe as high as 297 PSIG and 130 degrees F. A properly charged evaporator coil will be operating with about 10-15 degrees of superheat and the condenser coil with 6-10 degrees of sub-cooling. A dirty condenser can drive the pressures and temperatures up on both sides; units with thermal expansion valves are more predictable than those with piston or capillary tube type metering devices.
Newer machines using R-410 will operate at the same temperatures, super-heats and supercooling, but, of course, the pressures will be different because it is a much higher pressure gas.
Sometimes a AC unit with an unusually large condenser coil will run at a little lower head pressures and more sub-cooling, but the low side will be about the same. This situation will let the machine run at high efficiencies.
An interesting thing is that the evaporator coil has to run about 10 degrees colder than the discharge air temperature, ie, the coil leads the air. This is because it is impossible to cool the air down to the same temperature as the coil.
__________________
Who is so ignorant as not to know that knights-errant are beyond all jurisdiction, their only law their swords, while their charter is their mettle and their will is their decrees? Don Quixote
HVAC
Re: HVAC
