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Thread: drawers

  1. #1
    Join Date
    Mar 2003
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    373

    Question

    any suggestions for how refrigerated drawers should best be controled,
    have a set of 12, 3 cabinets, 3 evaporators, on one compressor,remote, about 40 feet away, and the amount of opening and closing these units go through, and customer tells me that for 3 years have never worked right,
    last night installed 3 solenoids and cold controls so that each evapor. has control of itself, instead of the pressure control.....
    or would you suggest eprs?
    or other thoughts.
    hem

  2. #2
    Join Date
    Jul 2000
    Location
    Guayaquil EC
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    10,421
    What's the history on these? Have they had evaporators freezing up a lot or what? Is there a defrost timeclock on this system?

  3. #3
    Join Date
    Mar 2003
    Posts
    373

    reply

    don't have much of a history, I have done work in other locations of this owner, but not in this exact location, maintenance man telling me that they have had alot of trouble with units running too warm (could be iced up?)
    I worked on 4 units last night till 4 a.m. (health inspector due back this morning)
    get this
    one of the other units had both evaps frozen, turned compressor off, after restarting iced up again by 8:30 am this morning, installed new cold controls, (rankin constant cut in 37 deg f) even in off position wouldn't close solenoid..... like what????
    ripped apart all the wiring and found that someone had six inches back from cold control, skinned off alittle insulation and twisted the wires together and put tape over, looked like it was to hold the wire from coming in contact with the blade....took me two hours to find this, trying to work inside some of these tight confined under counter units !!! and wondering what kind of goof would do this, do they not understand the cold control concept... and what bypassing it like this does....
    enough ranting
    so who knows what the guys have done to these other units
    back to the first one
    2 drawr width, 2 high... so approx 60 wide, cab. about 36 deep and 28 high... 1300 btu sound right????
    I think they have DF130 in there
    too small,??? I will have to check what compressors they have on each, by 4 am was alittle past taking down s/n and m/n's
    hem

  4. #4
    Join Date
    Dec 2001
    Location
    Ocean Pines, MD
    Posts
    6,996

    More info.

    What brand? What refrigerant?
    Had simular units, TXV's, R-22, orfices clogging. After tearing down, flushing and cleaning never had a problem again. Can't remember much else but they were a problem for some time after install till I was called. (Sometimes a new guy can see things frustration will overlook).

  5. #5
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,614
    T-stat, liquid line solonoid and time clock for defrost 4 times a day!

  6. #6
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215

    Re: reply

    Originally posted by hem057

    one of the other units had both evaps frozen, turned compressor off, after restarting iced up again by 8:30 am this morning, installed new cold controls, (rankin constant cut in 37 deg f) even in off position wouldn't close solenoid..... like what????


    Let's just clarify this.

    You're trying to use the cold control to operate a liquid line solenoid???

    If so, you're on the wrong track.

    A constant cutin cold control is supposed to eliminate the need for a defrost clock, in addition to controlling temp. It does this by sensing coil temperature, not air temp. It should never close the contacts until the evaporator coil itself reaches 37 degrees. (You'll be seeing a 47 degree air temp, give or take, at this point.) The contacts then open (shut down) at the desired setting. The contacts in these controls are intended to carry the load of the compressor.

    If you're trying to pump down the units with a solenoid being controlled by this cold control, you're wasting your time and money installing the solenoids. Just make sure that the cold controls are in contact with the evaporator coil, and wire them in series with the compressor overload, and pressure controls, on/off switches, etc.

    If those 37 degree constant cutin controls are properly installed, you won't have ice-up problems with these units, because the compressor just plain won't run until the coil is 5 degrees above the freezing temperature of distilled water. (Condesation.)

    I understand that they had your control circuit bypassed, but solenoid valves on these units is like an elevator in an outhouse, unless you're gonna go with separate temperature controls and defrost clocks for each.

    All that said, all the drawer units that I have worked on were not blower coils, but gravity. Thus, they did not utilize cold controls, but rather a pressure control for single drawer systems, or EPRs for multiple evap systems.

    (Similar to the combination sandwich tables that have ice rails.)

    Maybe I'm misunderstanding you, (and if I am, I apologize, but please clarify) but it sounds like something is seriously misapplied.

  7. #7
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
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    4,614
    Dave this unit has multiple circuts on one compressor.

    I think you will have issues with the constant cut-in controlls since the evap will get really cold fast with only one case calling.

    I think t-stat and ll sol is the way to go. I also believe that a time clock is needed.

  8. #8
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
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    13,215
    Originally posted by Freezeking2000
    Dave this unit has multiple circuts on one compressor.

    I think you will have issues with the constant cut-in controlls since the evap will get really cold fast with only one case calling.

    I think t-stat and ll sol is the way to go. I also believe that a time clock is needed.
    Or EPRs, in this instance. I've seen a few set up that way.

  9. #9
    Join Date
    Mar 2003
    Posts
    373

    Hmm further to that

    sorry, I wanted to reply this a.m., but had to go out, I always appreciate your comments dave (and others), I can see by the expressions you make that you have a wealth of experience,
    this particular cabinet has 3 evaps on one compressor, so wiring in cold controls to the compressor, well it would run with only one evap calling, but all would get cooling, and I wanted to try to use what was already there, and then not wanted to try to run 60 feet of wiring back to the condensing units, I just used the 120 volts available by the fan, wired in the cold control to the solenoid, and set up the pressure control to pump down when all three evaps are satisfied,... but I wanted some input into changing over to eprs, and will price and discuss this with the customer, I think I will price in larger evaps too, I think the DF130 are too small for the cabinet size,.
    to answer the other ?'s raised, this an R22 system, no cabinet maker named, I think it looks like an Astor cabinet, (? heard of them?)
    There are four condensing units in a mechanical room about 40 - 60 ft. away, some one has installed 4 defrost clock (not needed if the systems are set up properly as pointed out by dave, but I am working with what is already there, and working after others have butchered things, familiar with that?) hooked up three, one not tied in yet, soooo
    and these are fans type evaps....
    misapplied yes, but trying to get the customer running without re inventing every..... but will price eprs because I think it is a better way to go.... thoughts on that????
    thanks
    hem

  10. #10
    Join Date
    Jan 2002
    Posts
    1,895
    Epr's will help but any drawer setup I have ever seen in a kitchen will need some sort of a defrost system. one other thing to ponder just how long will the compressor last with the 3 solonoids ?

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