It's amazing that people won't take winning tips straight from the horse's mouthOriginally posted by Andy Schoen
airworx, you're a bit confused a bit here. Let me help you out.Originally posted by airworx
you guys are wrong however about how a txv works.
if you overcharge a system that has a txv and we are not talking about an orfice. but a txv will close off to keep the superheat up to its setpoint say 15 degrees. as more refrigerant is added it will have to close off more and more to keep the superheat up and that will cause the suction pressure to drop.
Suction pressure is simply a function of heat load on the evaporator and your compressor/condenser capacity. If the TEV is operating properly, it will modulate refrigerant flow such that it will increase refrigerant flow into the evaporator at higher load conditions, thus raising suction pressure, and reduce refrigerant flow into the evaporatir at lower load conditions. This is due, of course, to the fact it controls superheat at the evaporator outlet. It does this function much better than a capillary tube or fixed restrictor.
The key here is your heat load on the evaporator. It is the primary variable in determining your suction pressure.
The TEV doesn't care about an overcharge system. It will continue to control superheat regardless. An overcharged system, however, will reduced your compressor's capacity and efficiency, which will cause higher than normal suction and discharge pressures.
You might find the following of interest. http://www.sporlan.com/10-9.htm I wrote its original version