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  1. #1
    Join Date
    Oct 2003
    Posts
    134
    Could anyone please tell me how to set up a three compresser rack,running medium temp systems, for proper operation of compressers?

    the compressers have cut in/out mechanical pressure switches, the refrigerant is r22.

    Any help is greatly appreciated as I'm working in the field and treading water desperately trying to keep my chin above the water!

  2. #2
    Join Date
    Oct 2003
    Posts
    134

    oops!

    My question was-how should the compressers operate-should they run constantly, or should they cycle off in sequence?

  3. #3
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215
    I need to hear the following:
    • Capacity of each compressor. (Model #'s???)
    • Minimum desired evaporaor temperature.
    • Are there any hot gas defrost systems?
    • Are any of the system defrost cycles overlapping?
    • Are there anti-short cycle timers on the compressors?


    Then, I can tell you were to set what.

    But I'm gonna tell you that you need to sell this customer an energy management system. Seriously. 21st century here.

  4. #4
    Join Date
    Oct 2003
    Posts
    134
    copeland model 3ds, overlapping defrosts, electric defrosts, about 30 degree coils.

    is there anywhere I could learn more about setting up racks on the web, or are there any books which you could recommend?
    Thank you.

  5. #5
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215
    Not that I know of.

    If you could be more specific on the compressor capacity, I can tell you where to set that.

    3D's have a rather wide capacity range.

    30 degree evaps? That's rather high.

  6. #6
    Join Date
    Jan 2004
    Location
    Earth
    Posts
    4,879
    It never ceases to amaze me how someone can spend 20-30 grand on a rack, then cheap out on the controls.

    It's like buying a BMW, with a am radio and vinyl interior.
    A Diamond is just a piece of coal, that made good under pressure!

  7. #7
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215
    It's probably an old one. I take care of a few that run on either solid state suction pressure controls, and even some like that one, that's running EM pressure switches.

    No big deal, but the setup isn't just "aim at ___psi", and hope for the best.

  8. #8
    Join Date
    Jan 2004
    Location
    Earth
    Posts
    4,879
    Last year I set 3 new units with gang clocks and pressure controls. The supermarket that bought them would have paid for the good stuff.

    The people that sold them only spec gang clocks and pressure controls. They are used to selling in the caribbean.

    From what I hear over there your lucky if the guys know how to change a access valve cap. So programing a modern controler is out of the question.

    Your right Dave, old time controls work just fine, if set up right. They just cost a little more to run.
    A Diamond is just a piece of coal, that made good under pressure!

  9. #9
    Gang clocks and pressure controls are how a lot of Albertson's racks are set up.

    Their A/C systems are more sophisticated than their racks!!! It's truly bizzar.

    Their a/c are on control 4000's. A store I was at today had a pair of huge A/C systems named "Seasons 4". They tie into the comtrol 4000.

    Nice air conditioners!


    It amazes me how these particular markets are NOT the leaste bit interested in saving energy!

  10. #10
    Oh ... and I got another question about markets .... is it the norm for the store managers to all drag their leftover junk and store it in and leading to the motor room?


    So much junk you have to spend fifteen minutes before you can clear a path to get a new compressor delivered?

    Are all store managers slobs like this? It's a fire hazard!!! It's a safety hazard!!!

    They block the front of large electrical panels. They block access to some of the store's A/C system! They hinder PM's as well as emergancy service!


    I'd like to get a saz-all, cut it all up into foot long pieces, hire a bunch of college kids and carry it to the store managers office where it would be neatly stacked. Taking up each and every square inch of his workspace!!!
    And then foam the whole room in place, so that crap wouldnt migrate back to the motor room!




  11. #11
    Join Date
    Jan 2004
    Location
    Earth
    Posts
    4,879
    They don't put it all in there, some of it goes on top of the coolers.
    A Diamond is just a piece of coal, that made good under pressure!

  12. #12
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    No matter how many times your going to tell them over the next few years, your going to see the same thing. It gets to be comical after awhile. One time I walked up to one and this is after probably ten times before I have told him. I walked up and said. The rack room looked great. You might want to think about storing the new christmas lights and decorations your getting in up there. We both just laughed.

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