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  1. #1
    Join Date
    Apr 2010
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    Ontario
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    464

    Charging by sight glass

    When charging a refrigeration system by sight glass and its been off for hours, the case is warm. Do you clear the sight glass as soon as you can when you first restart the system, or let the case/product come down to its design temperature range and then finish charging to clear the sightglass.
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  2. #2
    Join Date
    Mar 2010
    Location
    Morgan Hill Ca.
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    Quote Originally Posted by Peztoy View Post
    When charging a refrigeration system by sight glass and its been off for hours, the case is warm. Do you clear the sight glass as soon as you can when you first restart the system, or let the case/product come down to its design temperature range and then finish charging to clear the sightglass.

    Technically when the case is "warm" the system is overloaded, the sight glass is not there for charging, your thermometer is....

    In all seriousness, it depends on much more than what you wrote. Receiver?, TXV?, Cap tube?, type of refrigerant?...

    Not as cut and dried as you are trying to make it.

    GT
    If a day goes by and you have learned nothing, I hope you got a lot of sleep.

  3. #3
    Join Date
    Jan 2010
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    5,812
    Is it a indoor or outdoor condensing unit ? This could make a big difference.

  4. #4
    Join Date
    Apr 2010
    Location
    Ontario
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    464
    TXV, receiver, R22, reach in cooler.
    I was thinking when you first start up the txv would be fully open because of the high load.
    Later as the cooler comes down to temperature the txv would be more closed, the liquid line would have more refrigerant backing up in it, the sight glass would then clear when the system was running in its normal range.
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  5. #5
    Join Date
    Mar 2010
    Location
    Morgan Hill Ca.
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    Quote Originally Posted by Peztoy View Post
    TXV, receiver, R22, reach in cooler.
    I was thinking when you first start up the txv would be fully open because of the high load.
    Later as the cooler comes down to temperature the txv would be more closed, the liquid line would have more refrigerant backing up in it, the sight glass would then clear when the system was running in its normal range.

    This would be accurate.... Hence why I said the system would be overloaded.. So I guess to answer your question, the charge should be verified when the box is close to set point, which in essence is where it will be running most of the time.

    GT
    If a day goes by and you have learned nothing, I hope you got a lot of sleep.

  6. #6
    Join Date
    Oct 2011
    Location
    Chicagoland Area
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    4,319
    Quote Originally Posted by Peztoy View Post
    TXV, receiver, R22, reach in cooler.
    I was thinking when you first start up the txv would be fully open because of the high load.
    Later as the cooler comes down to temperature the txv would be more closed, the liquid line would have more refrigerant backing up in it, the sight glass would then clear when the system was running in its normal range.

    Correct
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  7. #7
    Join Date
    Apr 2010
    Location
    Ontario
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    464
    Air cooled condensing unit in the ceilling.
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  8. #8
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    Jan 2010
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    5,812
    Is it a pump-down system ?

  9. #9
    Join Date
    Apr 2010
    Location
    Ontario
    Posts
    464
    Thanks for all your feed back.
    Not a pumpdown system.
    No suction to liquid line heat exhanger.
    Remote condensing unit. Not a self contained case.
    Got this quoted job from another guy. I replaced the compressor. 5 Lbs was reclaimed. I put 4 1/2 Lbs back in. Today I was later told the compressor was making noise before it quit. Now I'm glad I held back on the charge. If this wasn't quoted I'd want to go back to check a little deeper for compressor failure.
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  10. #10
    Join Date
    Jul 2007
    Location
    Mount Airy, MD
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    7,278
    Thread relocated to the refer section

  11. #11
    Join Date
    Feb 2001
    Location
    Anaheim, CA
    Posts
    65
    Make sure that this system does not have a suction to liquid line sub-cooler. I once had trouble clearing a sight glass on an R-12 system in the same manner. I discovered that the sub-cooler had internally ruptured and hp liquid was short circuiting into the suction line.

  12. #12
    Join Date
    Jan 2010
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    5,812
    So is the systems down or what ?

  13. #13
    Join Date
    Apr 2010
    Location
    Ontario
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    464
    I've seen sightglasses where it seems to just flow through. I had this one almost cleared. A little more gas would have done it.
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