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  1. #1
    Join Date
    Aug 2003
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    this is for the guys that were asking for reference to my comments on another post.

    copeland mandates a minimum compressor suction superheat of 20*.

    exerted from the heatcraft refrigeration installation manual
    "h-im-64d" a suction line superheat of 30-45 is to be maiuntained...

  2. #2
    Join Date
    Jan 2002
    Location
    Fort Worth\Dallas, Texas
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    1,706
    What kind of freon and evap temp is this refering to?

  3. #3
    new one on me. the only way any system should run that high of superheat is on an captube or orfice systems and then under certain circumstances.
    do it on a freezer and youll be changing out the captubes because the compressor windings are breaking down.

  4. #4
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    Aug 2003
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    lwarren
    did not specify. but if you wanna discuss further let me know. all in the interest of developing/ refining skills.

    so as it turns out i did in fact mis apply the information. copeland says only 20*. carlyle is a range i am digging for it. tecumseh is a range, looking for it as well. none as i recall specified which systems or evap temps.



    [Edited by hvac3901 on 07-01-2004 at 12:12 AM]

  5. #5
    If you maintain 20 to forty .... it doesnt matter which refrigerant or system this is on.

    The unit needs to run cool. Not too hot and not to cold either.

    Make sence?


  6. #6
    Join Date
    Dec 2003
    Posts
    1,739
    20 at the compressor, leads a lot a variables as to the length, I have heard that on res units, and they can be 10 to 50 feet away from the evap, I guess the comp. people want to ensure that the don't get slugging, sounds to general, rule of thumb thing.
    there but for the grace of god, go all of us

  7. #7
    Join Date
    Apr 2001
    Location
    Camel City, NC
    Posts
    6,233

    Comp. Superheat

    I've heard 20>26 from copeland rep. Have found different on charging charts with AC's and HP's. From what I've read here 20 is min. on racks if refrigeration is included in this.
    Be safe not fast. body parts don't grow back

  8. #8
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    Isn't that 20° at the compressor suction valve? So, that heat would also include heat from the motor windings.

  9. #9
    Join Date
    Aug 2003
    Posts
    1,311
    jrbenny
    6-8 or 10-12 inches away from the compressor inlet or service valve. whichever it is its not exactly at the inlet.

  10. #10
    you have to remember also that it dependeds if you have a orfice or txv. on orfice systems you can't control superheat when charged properly it will depend on temperture as to what the superheat will be like from 0 to 45 degrees.

    on txv systems you charge by subcooling and the superheat should be anywhere from 8 to 25 degrees. the higher the superheat the less efficient the machine becomes.
    superheat values for exvs on flotronic systems dependeds on the eprom chip. usually they range from 2 to 7 degrees superheat.


  11. #11
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    Originally posted by hvac3901


    copeland mandates a minimum compressor suction superheat of 20*.

    Where did you get this number?

  12. #12
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    Originally posted by hvac3901
    jrbenny
    6-8 or 10-12 inches away from the compressor inlet or service valve. whichever it is its not exactly at the inlet.
    I think you've been given some bad info. When you measure superheat, it is at the service valve, and should be 5 to 45° if on a piston system or 8-12° if on a TEV system.

    The 20-30° that you quote is suction superheat at the valve plate.

    Why would every unit manufacturer completely disregard Copeland's superheat requirements? Yep, that's right. They don't because the number you've quoted is in regards to a superheat that you can't measure.

  13. #13
    Join Date
    Aug 2003
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    1,311

    quote:
    --------------------------------------------------------------------------------
    Originally posted by hvac3901


    copeland mandates a minimum compressor suction superheat of 20*.


    --------------------------------------------------------------------------------

    Where did you get this number

    jrbenny
    uhhh, out of the copeland manual.

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