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  1. #1
    Join Date
    Sep 2011
    Posts
    85

    5 ton split, fixed orifice, sweaty compressor

    My superheat is too low? I charged it with 100+ ambient at 3-5 superheat. Was i pushing it too close? Yesterday i ran the system, about 90 degree ambient and the compressor was sweating. I didnt have time to hook up the gauges, heading back today.

    (told them not to run the system)

  2. #2
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,058
    Quote Originally Posted by wdshea View Post
    My superheat is too low? I charged it with 100+ ambient at 3-5 superheat. Was i pushing it too close? Yesterday i ran the system, about 90 degree ambient and the compressor was sweating. I didnt have time to hook up the gauges, heading back today.

    (told them not to run the system)
    Low load/ air flow overcharged, lots more info needed.

  3. #3
    Join Date
    Sep 2011
    Posts
    85
    Air flow is good, , indoor air temp at 81, i dont know the RH

  4. #4
    Join Date
    Nov 2005
    Posts
    1,350
    lots more info needed. Sub-cooling would be nice.
    I STARTED WITH NOTHING, AND I STILL HAVE MOST OF IT!

  5. #5
    Join Date
    Sep 2011
    Posts
    85
    Why is subcooling important with a fixed orifice? B/c if it's high it means i'm overcharged?

    Furthermore, don't you need to know the SEER of the unit as well to know what the subcooling should be?

  6. #6
    Join Date
    Apr 2002
    Location
    most of the time in the Philippines
    Posts
    1,211
    Get yourself a charging slide rule from Trane or Carrier [or both]. I used to use them on all brands, Worked fine.

  7. #7
    Join Date
    Nov 2005
    Posts
    1,350
    Quote Originally Posted by wdshea View Post
    Why is subcooling important with a fixed orifice? B/c if it's high it means i'm overcharged?

    Furthermore, don't you need to know the SEER of the unit as well to know what the subcooling should be?
    You are answering your own questions, of course high sub cool and low super heat will tell us more then just low super heat. Ideal super heat at the compressor is between 18-22F, if you have 3-5F and your sub cooling is high, say above 10F, you may have too much gas in there. Some compressor manufacturers will even specify higher super heats, Copeland likes 35F.
    I STARTED WITH NOTHING, AND I STILL HAVE MOST OF IT!

  8. #8
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    2,847
    I doubt a compressor around here running 35° SH would last very long before cooking the oil!

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,754
    Quote Originally Posted by wdshea View Post
    Air flow is good, , indoor air temp at 81, i dont know the RH

    Where do you get a gauge/meter that says air flow good?
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,754
    Quote Originally Posted by wdshea View Post
    My superheat is too low? I charged it with 100+ ambient at 3-5 superheat. Was i pushing it too close? Yesterday i ran the system, about 90 degree ambient and the compressor was sweating. I didnt have time to hook up the gauges, heading back today.

    (told them not to run the system)
    What was the indoor wetbulb temp when you charged it.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  11. #11
    Join Date
    Nov 2005
    Posts
    1,350
    Quote Originally Posted by KB Cool View Post
    I doubt a compressor around here running 35° SH would last very long before cooking the oil!
    you may want to check copeland's web site.
    I STARTED WITH NOTHING, AND I STILL HAVE MOST OF IT!

  12. #12
    Join Date
    Nov 2005
    Posts
    1,350
    Quote Originally Posted by allstar08 View Post
    you may want to check copeland's web site.
    The minimum super heat per Copeland's web site is 20F. I have attended a few classes on this and have plenty of verification. I usually run them 18-22.
    I STARTED WITH NOTHING, AND I STILL HAVE MOST OF IT!

  13. #13
    Join Date
    Jun 2001
    Location
    Northwest Indiana
    Posts
    1,302
    I have interpted the 20 superheat as a guide line to keep you out of trouble.
    It would be very difficult to maintain no lower than 20 on a fixed orifice close coupled residential split system. IMHO
    Just to clarify, was that for scrolls and recips?
    If you cant fix it right, try again.

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