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  1. #14
    Join Date
    Mar 2008
    Location
    arkansas
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    78
    Quote Originally Posted by smilies View Post
    It goes along the lines of "superheat never killed an evaporator." What is more important, evaporator superheat or compressor superheat?

    Wait until you learn about discharge superheat
    i think both but evap superheat is what you want to measure and comp superheat will show you if the refrigerant is cooling the comp right

  2. #15
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    2,877
    I usually find on the restricted systems liquid line will be cool. On the undercharged systems liquid line will be warm. On systems just about flat on charge discharge line will not be hot. Alot of the little systems, no access valves are provided so i use alot of touch and feel before i pierce the line with my vise grip access tool.

  3. #16
    Join Date
    Jul 2008
    Location
    Denver, CO
    Posts
    4,229
    Quote Originally Posted by smilies View Post
    It goes along the lines of "superheat never killed an evaporator." What is more important, evaporator superheat or compressor superheat?

    Wait until you learn about discharge superheat
    Well here is the way I see it if your evaporator superheat is correct then you won't have a problem at the compressor because all of the refigerant will be vaporized before it hits the compressor. But will still beable to cool the compressors motor. Why do we have to make this so complicated? (compressor super heat, compressor discharge super heat) If your super heat is good and nothing has been modified then all is good, but thats just my opnion.
    Last edited by Tiger93rsl; 07-22-2008 at 11:40 PM.

  4. #17
    Join Date
    Jul 2008
    Location
    Denver, CO
    Posts
    4,229
    Quote Originally Posted by fishindad View Post
    i think both but evap superheat is what you want to measure and comp superheat will show you if the refrigerant is cooling the comp right
    Now that makes sense but if the line set has not been modified from the original design and the superheat (from the suction line off the evaporator) is correct then your compressor super heat will be just fine.

  5. #18
    Join Date
    Jan 2006
    Location
    DFW Metroplex
    Posts
    4,910
    Quote Originally Posted by Tiger93rsl View Post
    Well here is the way I see it if your evaporator superheat is correct then you won't have a problem at the compressor because all of the refigerant will be vaporized before it hits the compressor I just think all this talk about compressor super heat is a bunch of hog wash. But thats just my opnion
    It's not just floodback that will take out a compressor - how long do you suppose a refrigerant cooled pump will run with no refrigerant cooling?

  6. #19
    Join Date
    Jul 2008
    Location
    Denver, CO
    Posts
    4,229
    Quote Originally Posted by markettech View Post
    It's not just floodback that will take out a compressor - how long do you suppose a refrigerant cooled pump will run with no refrigerant cooling?
    I had to edit my post I spoke a little too soon, but my point is if nothing has been modified in the suction line to the compressor and your super heat is correct then the refrigerant in the suction line will be able to cool the compressor to the designed specification.

  7. #20
    Join Date
    Mar 2008
    Location
    arkansas
    Posts
    78
    I ssues before that the compressor overheats when I have 60+ sh comming back to the compressor, but the freezer box temp is also 60+, takes awile of heat absorbtion to get the correct cooling comming back, found when box temp gets below freezing or about 25 things make more sense. will that have any affect on theompressors life when this happens

  8. #21
    Join Date
    Mar 2008
    Location
    arkansas
    Posts
    78
    sorry work with to many hand tools cant type well

  9. #22
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    2,877
    Quote Originally Posted by fishindad View Post
    sorry work with to many hand tools cant type well
    Ya, what were you saying again?

  10. #23
    Join Date
    Jan 2005
    Location
    Veterans Home Yaphank, NY
    Posts
    2,309
    Contractor
    Service Tips
    Evaporator Vs. System Superheat
    Q: What is the difference between evaporator
    superheat and system superheat?
    Superheat varies within the system depending on
    where it is being measured. The superheat that the
    thermal expansion valve is controlling is the
    evaporator superheat. This is measured at the outlet
    of the evaporator. The refrigerant gains superheat as
    it travels through the evaporator, basically starting at
    0 as it enters the evaporator and reaching a
    maximum at the outlet as the refrigerant travels
    though the evaporator absorbing heat.
    System superheat refers to the superheat entering
    the suction of the compressor. Some people confuse
    system superheat with ‘return gas temperature.’ It
    should be remembered that superheat varies as the
    saturated suction pressure of the refrigerant varies.
    Return gas temperature is a temperature value measured
    by a thermometer or other temperature-sensing
    device. It does not vary because of pressure changes.
    Q: How much system superheat should I see at the
    compressor inlet?
    Compressor manufacturer's like to see a minmum of
    about 20 degrees of superheat at the compressor
    inlet. This is to assure them that no liquid refrigerant
    is entering the compressor.
    Tip Card
    10
    Form No. 2005DS-133 Issued 1/06
    Emerson Climate Technologies logo is a trademark of Emerson Electric Co.
    © 2006 Emerson Climate Technologies. Printed in the USA.

    Reading is Fundamental, and may cause a sudden burst of smarts.
    RAM Teaching Tomorrows Technicians Today.

  11. #24
    Join Date
    Jan 2006
    Location
    DFW Metroplex
    Posts
    4,910
    Quote Originally Posted by fishindad View Post
    I ssues before that the compressor overheats when I have 60+ sh comming back to the compressor, but the freezer box temp is also 60+, takes awile of heat absorbtion to get the correct cooling comming back, found when box temp gets below freezing or about 25 things make more sense. will that have any affect on theompressors life when this happens
    I'm having a rather hard time understanding the question here.

    Are you saying that you have a freezer box temp at +60F and the suction line temperature is +60F and the compressor is shutting down on overload, and you're wondering if this would affect the compressor's longevity?

  12. #25
    Join Date
    Mar 2008
    Posts
    257
    Quote Originally Posted by kbghdg View Post
    I usually find on the restricted systems liquid line will be cool. On the undercharged systems liquid line will be warm. On systems just about flat on charge discharge line will not be hot. Alot of the little systems, no access valves are provided so i use alot of touch and feel before i pierce the line with my vise grip access tool.
    I was wondering which supplier you use to obtain this type of access tool, as its seems like a handy thing to add to my tool pouch. Just kidding I have 2 pair in there now and I find the sheet metal folding type vice grips with the 3 inch plate jaws work great.

  13. #26
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    2,877
    Quote Originally Posted by frigeguy View Post
    I was wondering which supplier you use to obtain this type of access tool, as its seems like a handy thing to add to my tool pouch. Just kidding I have 2 pair in there now and I find the sheet metal folding type vice grips with the 3 inch plate jaws work great.


    I've never seen the 3 inch plate type vice grip peircer as this one get the job done. I've ran across a few systems that had those "temporary" allen screw access valves that some A$$hole left on for permanent use. And yes, they leaked. Clamp one of these visegrips types on the high and one on the low. Find out whats wrong with it. Recover and then braze in a permanent valve after the repair.
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