jonc5553
19-07-2010, 03:59 PM
I need help.
I've read that cap tube or fixed orfices are charged by superheat and Txv units are to be charged by subcooling. I have purchased a Fieldpiece hand-held meter SSX34. OK heres my confusion. If I'm working on a cap-tube system, first I have to find my target super heat. Inside wet bulb and outside dry bulb to get this target superheat. Say it tells me 12 target super heat. Then I read other articles that say you need 20-30 degree super heat at unit. If my meter tells me 12 then where does this 20-30 come from. Fieldpiece shows hooking up hose on suction sevice valve at unit and taking temp reading on suction line at unit. Theres the conflict. My meter tells me I want a 12 degree superheat and the article says 20-30.
The article I have is Mike Taitano Air Conditioning and Refrigeration Systen Evaluation Guide. His book does not say if its captube or TXV as far as the metering device, like it doesn't matter. I thought that when you check the super heat on a TXV you wanted to check your pressure at the leaving line of the evap. and line temp also, to get superheat value, if there is a port on line, 6- 12 degrees super heat. So am I thinking right, that you can also check superheat at unit and thats where you should have 20-30 superheat. I'm confused. Sorry for making this so long, this is also my first time posting.
I've read that cap tube or fixed orfices are charged by superheat and Txv units are to be charged by subcooling. I have purchased a Fieldpiece hand-held meter SSX34. OK heres my confusion. If I'm working on a cap-tube system, first I have to find my target super heat. Inside wet bulb and outside dry bulb to get this target superheat. Say it tells me 12 target super heat. Then I read other articles that say you need 20-30 degree super heat at unit. If my meter tells me 12 then where does this 20-30 come from. Fieldpiece shows hooking up hose on suction sevice valve at unit and taking temp reading on suction line at unit. Theres the conflict. My meter tells me I want a 12 degree superheat and the article says 20-30.
The article I have is Mike Taitano Air Conditioning and Refrigeration Systen Evaluation Guide. His book does not say if its captube or TXV as far as the metering device, like it doesn't matter. I thought that when you check the super heat on a TXV you wanted to check your pressure at the leaving line of the evap. and line temp also, to get superheat value, if there is a port on line, 6- 12 degrees super heat. So am I thinking right, that you can also check superheat at unit and thats where you should have 20-30 superheat. I'm confused. Sorry for making this so long, this is also my first time posting.