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Thread: hey refer guys

  1. #1
    Join Date
    Dec 2006
    Location
    Middle Tennessee
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    11,347

    hey refer guys

    ok went to the job tonight (last call) walk in cooler (beer)

    its the first time i ever been to this job

    it has 2 mismatched evaps, a 2 fan evap with a 1 h/p cond. and a 3 fan evap with a 2 h/p cond.

    2 different stats for the same cooler

    cooler is 25 wide x 8 length x 7 foot ceiling,

    anyway the 2 hp comp. has wasted valves and its old, i am gonna replace the condenser

    i am probably gonna wire a relay to turn both compressors on and off at the same time thru 1 controller

    maybe i will slap a 1 minute delay between both stages for $hits and giggles

    or is there a different way anyone else would do it?

    my second thought was turning one stat (the bigger condenser) a few degrees lower than the other

    what option would you guys use, and can you see any advantages or disadvantages one way or the other


    .

  2. #2
    Join Date
    Sep 2005
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    florida
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    I would go with one controler with at least 1 min or longer delay on bigger
    unit.just my 2 cent's
    I love the smell of phosgene first thing in the morning:

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  3. #3
    Join Date
    May 2007
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    747
    The advantage of turning both compressors on/off at the same time would be better defrosting during the off cycle. It is very difficult to get two stats to work in sync, one of the units is going to run (and ice) more. I wonder, though, why there are two units to begin with. Is there something about the construction or loading that might cause one end to overcool if both units run at the same time? If that is a concern, I would use an electronic stat on each unit so they can be set on the exact same setting with no guesswork.

  4. #4
    Join Date
    Jan 2005
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    San Antonio Texas.
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    http://customer.honeywell.com/honeyw...aspx/T775B2040

    I like to use these controllers. Very reliable and accurate and you can program each set of contacts seperately.

    Me, Id have them both on/off at the same time unless the 2 Hp could handle the load all by itself and the 1 hp could be for heavy usage periods/quick pull down.

    If the box needs all 3 Hp then why bother with a few degrees colder as the capacity of the 2 hp is at its minimum at temp and will run longer to get the box down those few more degrees, ie unneccesary wear on the comp.
    Every day that goes by is another day that you could have done what you intend to do tommorow.

  5. #5
    Join Date
    Mar 2007
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    wedged in freezer shelf
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    The times I see this an interior wall was removed. The smaller is usually a freezer that makes a better cooler. What direction are the fans blowing with relationship to the 25 ft. wall ?
    “If You Can Dodge A Wrench You Can Dodge A Ball”

  6. #6
    Join Date
    Oct 2007
    Location
    The rainy state
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    172
    heres a thought, since one comp is trashed, why not resize for the correct hp comp and not have to peice meal the controls,defrost and you end up with a better system and a happier customer.

  7. #7
    Join Date
    Jan 2007
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    maine
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    790
    good question air.. Ive actually been wondering about this.. As i picked up a few new stores and 3 of them have walkins with 2 condensing units , one evap per condensing unit and a stat for each.. Yet to work on any of them but was wondering the best way to go.. so lets hear it guys

  8. #8
    Join Date
    Mar 2005
    Location
    burlington county n.j.
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    9,764
    i have always run them as 2 totally independent systems usually one stat set 2-3 degrees colder than the other. time clock defrost pump down system. have never had a defrost problem and i usually run my beer walk-ins 33-34 degrees. usually switch the lead- lag units once a year or so.

  9. #9
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
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    4,656
    Like the post before me, keep one unit running for lower energy costs. Keep the second stat 3-4 degrees warmer
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  10. #10
    Join Date
    Jun 2005
    Location
    Las Vegas NV
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    1,152
    Quote Originally Posted by Airmechanical View Post
    ok went to the job tonight (last call) walk in cooler (beer)

    its the first time i ever been to this job

    it has 2 mismatched evaps, a 2 fan evap with a 1 h/p cond. and a 3 fan evap with a 2 h/p cond.

    2 different stats for the same cooler

    cooler is 25 wide x 8 length x 7 foot ceiling,

    anyway the 2 hp comp. has wasted valves and its old, i am gonna replace the condenser

    i am probably gonna wire a relay to turn both compressors on and off at the same time thru 1 controller

    maybe i will slap a 1 minute delay between both stages for $hits and giggles

    or is there a different way anyone else would do it?

    my second thought was turning one stat (the bigger condenser) a few degrees lower than the other

    what option would you guys use, and can you see any advantages or disadvantages one way or the other


    .
    Sounds like this might be a display cooler with glass doors? Evaps mounted along the 25' wall?

    If so, I design many display boxes with two systems, although normally the same HP. I'd probably leave them on separate t'stats. One side of the cooler glass doors might be used more often than the others. The load will vary from one end to the other. Or it could have been an add on. Are the evaps mounted evenly along the wall or is at a after thought cluster?

  11. #11
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    thanks for opinions guys, evaps are running the length of the cooler (not one on each end)



    .

  12. #12
    Join Date
    Nov 2007
    Posts
    162
    If you are replacing one of the condensing units already, you may want to consider sizing a unit that will take care of the whole load and run one condensing unit for both evaps. (depending on how hard it would be to re-pipe the coils and how old the 1 h.p. cond. unit is).

  13. #13
    Join Date
    Nov 2005
    Location
    Haymarket VA
    Posts
    642
    Quote Originally Posted by nwrscold View Post
    If you are replacing one of the condensing units already, you may want to consider sizing a unit that will take care of the whole load and run one condensing unit for both evaps. (depending on how hard it would be to re-pipe the coils and how old the 1 h.p. cond. unit is).
    sounds good

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