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  1. #1
    Join Date
    Jan 2001
    Posts
    765

    approach to charging mcquay unit

    i am working on a bry air dehumidification system with mcquay condensing unit. this has a pre and post coil. the issue is the post coil. the 2nd stage was low on charge. i charged until sight glass was clear.(63#). when i was finished i had 390 hp 150 suction 4 lsc 3 superheat sight glass clear. the exv is controlled by bry air unit.my question is if there is an issue with exv should i charge till i achieve proper subcooling.Both circuits the compressors are both sweating completly over. my thoughts are the exv is wide open not allowing refrigerant to back up in condensor thus low subcooling low superheat. I dont have all the readings or answers just got thown into this installing contractor got removed from job.also I told plant manager we need to find leak. Not sure if system wasnt charged right or leak???

  2. #2
    Join Date
    Aug 2007
    Location
    Winter Haven, FL
    Posts
    4,379
    I don't know this particular unit, but you should be able to go into the programming and manually operate the exv. Close it down to 15% and see what your pressures go to. Its possible that the superheat sensor is out of range, or the valve doesn't want to operate anymore.

  3. #3
    Join Date
    Jan 2001
    Posts
    765
    yeah it was one of those friday at 4pm jobs. i let them know the issues. That would be the next step.

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