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Thread: Sub Cooler

  1. #1
    Join Date
    Apr 2010
    Location
    Richmond, Virginia
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    311

    Sub Cooler

    How do you determine if a sub-cooler is bad on a rack? Alarm set point is above 80 degrees. When I got there was reading 91. Being feed from med. temp. rack with a sport. Backed sport all the way out to rack pressure and turned in the manual stem in the liquid solenoid valve. TXV seemed to be feeding. Suction comming from med. temp. rack was hot and would never get cold after about an hour. I suspect the heat exchanger has a leak in it but not sure, how can I verify? Or is the TXV not feeding? Help !!!! Both racks are R22 Luckly if the sub cooler is bad!

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
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    25,721
    Quote Originally Posted by NANOTECH View Post
    How do you determine if a sub-cooler is bad on a rack? Alarm set point is above 80 degrees. When I got there was reading 91. Being feed from med. temp. rack with a sport. Backed sport all the way out to rack pressure and turned in the manual stem in the liquid solenoid valve. TXV seemed to be feeding. Suction comming from med. temp. rack was hot and would never get cold after about an hour. I suspect the heat exchanger has a leak in it but not sure, how can I verify? Or is the TXV not feeding? Help !!!! Both racks are R22 Luckly if the sub cooler is bad!
    Ok, let's break it down.

    TXV seemed to be feeding.
    Did you check superheat?

    I suspect the heat exchanger has a leak in it but not sure, how can I verify?
    You don't have a leak in the HX. Here's why:

    Suction comming from med. temp. rack was hot and would never get cold after about an hour.
    This, of course, assumes that the suction line referred to is the suction from the subcooler. Since it would be leaking liquid directly into the suction line, a leaking or ruptured heat exchanger like that would cause a VERY cold suction line.

    Now, to FIX this thing.

    What type of subcooler? If it is one of those tube in tube types, stop right now and don't waste any more time. They just don't work.

    If it's a brazed plate style HX, first, verify proper liquid to the unit, check the power element and see what you find.

  3. #3
    Join Date
    Apr 2010
    Location
    Richmond, Virginia
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    311
    I'll have to peel the insullation off of it today to see what type it is, and check the superheat on the TXV. I'll post back tonight, thanks JP !

  4. #4
    Join Date
    Sep 2008
    Location
    Western PA
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    Quote Originally Posted by NANOTECH View Post
    I'll have to peel the insullation off of it today to see what type it is, and check the superheat on the TXV. I'll post back tonight, thanks JP !
    You don't need to do that.

    If the HX is roughly cube shaped, then you've got a brazed plate HX.

    If it almost looks like part of the liquid line then it is a tube in tube type.

  5. #5
    Join Date
    Nov 2009
    Posts
    385
    Don't over complicate things. Set the SPORT valve on the subcooler suction to +35 SST (in most cases). Check the superheat of the subcooler TEV(s). Then go from there.
    "Don't wish it were easier, wish you were better"

  6. #6
    Join Date
    Feb 2008
    Location
    California
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    2,066
    Quote Originally Posted by NANOTECH View Post
    Backed sport all the way out to rack pressure and turned in the manual stem in the liquid solenoid valve. TXV seemed to be feeding.
    I would look into why you needed to do these things.

  7. #7
    Join Date
    Apr 2011
    Location
    Palmdale ca with my brothers
    Posts
    44
    You sure the rack being sub cooled has enough gas?? If the rack is short you wont get temp. Also what about the rack that is feeding the subcooler, is it short on gas??

  8. #8
    Join Date
    Sep 2006
    Posts
    155
    bringing receiver levels up solves many a subcooler issues.

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