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Thread: Superheat

  1. #1
    Join Date
    Aug 2012
    Posts
    7

    Superheat

    Hi guys new here and need help

    I have been outside the hvac business for a while now but
    my brother asked me to install a new ductless unit (split) in his home

    well the indoor unit is the new piece i have installed
    the old one has a leak in the evaporator the outside unit is fine

    the unit needs to be charged with some f22
    so i am using the superheat meathod to charge it


    i just want to make sure if my calculations is right

    Outside temp: 113F
    Indoor temp: 80F

    required superheat: 33F

    _________________________________

    Low line Temp: 32
    Low line Pipe Temp: 19

    current superheat: 13




    should the superheat be 33F ???

  2. #2
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Ductless units only have one service port on the high side ( not a hp)

    How could you get ssh ?

  3. #3
    Join Date
    Aug 2012
    Posts
    7
    Low Line = Large Diameter pipe

    not the small one ( high side)

  4. #4
    Join Date
    Aug 2012
    Posts
    7
    suction pressure converted to temp: 32F
    suction line temp: 19F

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,338
    Installation manual. Charging scale. Combine the two and see if your results improve. That's all we can really tell you here due to DIY restrictions of this section.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #6
    Join Date
    Aug 2012
    Posts
    7
    I just want to know if 33 superheat is fine ?

  7. #7
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,659

  8. #8
    Join Date
    Oct 2002
    Posts
    1,306
    minisplits I work on have expansion device in the outside unit. Both pipes going to inside unit are suction. Service valve is suction. I'd feel fine with 10-20 SH.

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,058
    Quote Originally Posted by cuadro View Post
    suction pressure converted to temp: 32F
    suction line temp: 19F

    So your suction line pressure is 58PSIG, and your suction line temp is 19F? Or is it 19C.
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  10. #10
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    Anytime a repair is done on a mini, you should recover the entire charge and weigh in a new charge after a thorough evacuation process. As stated by others, both lines in the lineset are normally insulated because the EEV is located inside the outdoor unit, thus the service tap is low side but before the evaporator and your gauge set is reading saturated pressure of evaporation, primarily at the indoor unit.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  11. #11
    Join Date
    Aug 2012
    Posts
    7

    Right

    Quote Originally Posted by beenthere View Post
    So your suction line pressure is 58PSIG, and your suction line temp is 19F? Or is it 19C.
    We are Talking F

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,058
    Quote Originally Posted by cuadro View Post
    We are Talking F
    Then I would think either your gauge or your temp probe is inaccurate. Since that would indicate that your suction line is losing heat.
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    How many times must one fix something before it is fixed?

  13. #13
    Join Date
    Aug 2012
    Posts
    7
    no my set is brand new and i have another one the same result is showing on both

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