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  1. #1
    Join Date
    May 2003
    Location
    El Paso, TX
    Posts
    156

    Hmm BUBBLES IN SIGHT GLASS

    Is it possible to have a correct charge and still have bubble in the sight glass? 8ºSH, 10º SC, R-22
    COOL

  2. #2
    Join Date
    Aug 2012
    Posts
    2,325
    Yes, especially with mixed refrigerants txv's and high loads.

  3. #3
    Join Date
    May 2003
    Location
    El Paso, TX
    Posts
    156
    What do you mean?

    especially with mixed refrigerants txv's?
    COOL

  4. #4
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
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    5,821
    Bubbles in glass while sc is measured indicates noncondensibles.

  5. #5
    Join Date
    May 2002
    Location
    evansville indiana
    Posts
    942
    Possible non cons ....

    Do you have condensor fan cycling for head pressure control?

    This can also occur when the fan comes on after being off and is normal....
    mikeacman

  6. #6
    Join Date
    Aug 2012
    Posts
    2,325
    Quote Originally Posted by dukes13 View Post
    What do you mean?

    especially with mixed refrigerants txv's?
    did I studder?

  7. #7
    Join Date
    May 2003
    Location
    El Paso, TX
    Posts
    156
    evacuate system down to 445µ!
    +
    Quote Originally Posted by mikeacman View Post
    Possible non cons ....

    I jumped the switch to operate continuously,
    Do you have condensor fan cycling for head pressure control?

    This can also occur when the fan comes on after being off and is normal....


    NO mixed refrigerants.

    especially with mixed refrigerants txv's?
    COOL

  8. #8
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,296
    Quote Originally Posted by toocoolforschool View Post
    did I studder?

    Stuh-stuh-stuh-studder
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    It was working when I left...
    Liberalism-Ideas so good they mandate them

  9. #9
    Join Date
    Nov 2012
    Location
    PA
    Posts
    47
    R-22 is not a mixed refrigerant. Subcooling is the cooling after in has become 100% liquid (no bubbles). I would check to make sure your readings are correct and possibly a restriction before the sight glass.

  10. #10
    Join Date
    Mar 2011
    Location
    North Carolina Piedmont Area
    Posts
    407
    What is the tonnage for this system.
    Is this a split system and if so how long is the line set.
    What is the the size of the liquid line and the suction line.
    Where is the sight glass located, is it at the condenser or at the evaporator.
    Does this system use a TXV.
    What is the suction pressure.
    What is the head pressure, out door ambient temperature, and indoor temperature.
    Where are you measuring super heat, at the evaporator or at the compressor.
    If you are measuring at the compressor, why is the superheat so low.
    Have you verified correct air flow.

    Like Mikeacman asked, what are you using for head pressure control.

    The presence of flash gas or bubbles in the sight glass is not an accurate indication of non condensables in the system. For this you will need to identify all other probabilities first. Such as a low ambient condition and cycling of condenser fan motors. You must raise your head pressure to around somewhere in the range of at least 200 PSIG or 105 deg liquid saturation temperature first............

    _______________________________
    Trouble shooting is not part of the repair.......understand the symptoms and you will find the solution.

  11. #11
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    24,933
    Quote Originally Posted by alcomech View Post
    What is the tonnage for this system.
    Is this a split system and if so how long is the line set.
    What is the the size of the liquid line and the suction line.
    Where is the sight glass located, is it at the condenser or at the evaporator.
    Does this system use a TXV.
    What is the suction pressure.
    What is the head pressure, out door ambient temperature, and indoor temperature.
    Where are you measuring super heat, at the evaporator or at the compressor.
    If you are measuring at the compressor, why is the superheat so low.
    Have you verified correct air flow.

    Like Mikeacman asked, what are you using for head pressure control.

    The presence of flash gas or bubbles in the sight glass is not an accurate indication of non condensables in the system. For this you will need to identify all other probabilities first. Such as a low ambient condition and cycling of condenser fan motors. You must raise your head pressure to around somewhere in the range of at least 200 PSIG or 105 deg liquid saturation temperature first............

    _______________________________
    Trouble shooting is not part of the repair.......understand the symptoms and you will find the solution.
    This is the best answer.

  12. #12
    Join Date
    Apr 2007
    Location
    Kaufman county, Texas
    Posts
    9,628
    Quote Originally Posted by dukes13 View Post
    Is it possible to have a correct charge and still have bubble in the sight glass? 8ºSH, 10º SC, R-22
    Generally speaking a TXV requires liquid to operate correctly.

    But as for having bubbles with a given SC, yes it happens. The refrigerant is in motion inside a working system, not like on a work-bench where 1 degree SC=pure liquid. I generally work on RTUs and do not get a clear and reliable sightglass until around 16 SC.
    "You boys are really making this thing harder than it has to be". Me

    "Who ARE you people? And WHAT are you doing in my SWAMP!?" Shrek

    Service calls submitted after 3PM will be posted the next business day.

    I give free estimates [Wild Ass Guesses] over the phone.

    "Ain't nobody got time for that". Corny

  13. #13
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,419
    Quote Originally Posted by Tool-Slinger View Post
    Generally speaking a TXV requires liquid to operate correctly.

    But as for having bubbles with a given SC, yes it happens. The refrigerant is in motion inside a working system, not like on a work-bench where 1 degree SC=pure liquid. I generally work on RTUs and do not get a clear and reliable sightglass until around 16 SC.
    I've seen this on chillers with subcoolers on them. Seems like on those you get about 12 degrees before the thing clears. The first time I saw it I actually had 2 thermometers on there just to make sure I wasn't crazy.

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