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  1. #1
    Join Date
    Dec 2012
    Posts
    25

    Carrier 30GTN100 chiller

    I just inherited a carrier model# 30gtn100 This unit has two sight glasses. One is located right after a two core liquid line drier and the second is located in part of the EXVs body. The first sight glass does not flash at all and always has a full column of liquid no matter how many compressors and fans are running. The other sight glass that is located in the exvs body constantly flashes and never runs a full sight glass. Im just curious of the purpose of the second sight glass. The sight glasses are less than three feet apart.

  2. #2
    Join Date
    Apr 2012
    Location
    Louisiana
    Posts
    673
    Not sure but I would guess its to visually check exv position.

  3. #3
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    874
    Like Sicofthis said it is a visual check, If you were to see a full sight glass you would have some thermodynamic problems. The constant "flashing" you are visualizing is some of the liquid refrigerant boiling off the heat from the rest of the liquid so it gets cold enough to absorb the heat from the water passing through the chiller barrel. Remember you have a pressure differential across the valve the causes the temperature differential. -GEO
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  4. #4
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,718
    Flashing usually happens after the metering device like you are experiencing. The sightglass on the valve is the check EXV operation.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  5. #5
    Join Date
    Dec 2012
    Posts
    25
    Thanks for the info, I was thinking that the refrigerant was already passing through a metering device and boiling off but I wasn't sure. I have never taken one of these EXV's apart and I wasn't sure how they operate.

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