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Freezer floor

A leak shouldn't occur for many years (?)

I'm more concerned with performance, both as a condenser and as a frost guard. We have an air cooled on site currently and would keep it as a backup.

The load, IIRC, is about 20,000 BTUH.

Comments

  • Tony_8
    Tony_8 Member Posts: 608
    As a condenser

    I have a customer who bought a walk-in w/o a floor and set it up on a concrete floor in a garage.

    As you can imagine, 5 years later, the floor has heaved about 9 inches.

    His plan is to shut down in September and break out the floor and insulate w/ blue board, then re-pour.

    I think we should run bare copper tubing under the insulation and use it as a condenser, at the same time keeping the hoar frost from forming. The freezer is 16X24x8 feet and is kept at 10F for bagged ice storage (palletized). Where can I find a chart with the amount of tubing needed for a given HP and refrigerant ?

    TIA,

    Tony
  • Tony_8
    Tony_8 Member Posts: 608
    Anybody ?

  • don_144
    don_144 Member Posts: 27
    Hello Tony

    I would shy away from that idea,just the issue alone of having enough velocity to get the oil back to the compressor
    scare me.

    This hoar of ice you speak of..has me thinking your defrost
    cycle is to long.I've seen this in many of freezer where the humidity is put back from being evaporated off the air coil,not to mention people standing in the door way all day.

  • Empire_2
    Empire_2 Member Posts: 2,343
    Tony

    In my opinion, the ref piping that is under the ground being used as a condenser will not dissepate the heat created by the compressor. Even if you are below the freeze line your head pressure will climb. Another thought...At lower ambient temps, not good to have lo discharge temps and pressures.
  • Empire_2
    Empire_2 Member Posts: 2,343
    Tony

    In my opinion, the ref piping that is under the ground being used as a condenser will not dissepate the heat created by the compressor. Even if you are below the freeze line your head pressure will climb. Another thought...At lower ambient temps, not good to have lo discharge temps and pressures.
  • Tony_8
    Tony_8 Member Posts: 608
    the hoar frost

    is under the floor. It's present because the freezer is on 24/7 for 5+ years. I've read, somewhere in the past, of heaters under the floors of refrigerated warehouses. I thought, maybe, with a small load like this that my idea might fly.
  • Tony_8
    Tony_8 Member Posts: 608
    I figured

    the earth under the floor wouldn't be more than 50F and should take the heat well enough. A head pressure control would be appropriate. My concern is will it be enough heat to keep the frost from forming ?
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    My concern...

    Although in theory, your idea sounds like it will fly, there are a number of things you need to consider. The first being that there are no charts or tables that will provide you with the number of feet of tubing you would need to run to reject the system heat at a given horsepower and a given refrigerant.

    If you are able to determine the design conditions of the system, you can reverse-engineer the system with a pressure-enthalpy chart, calculating the capacity of the condenser that would be needed.

    Since you are looking, in essence to fabricate a large "hot-wall" type condenser, the resulting capacity may not be exactly what was originally calculated, which brings me to my next point.

    Once the tubing is buried, how do you plan to access it in the event of a leak or in the event that the condenser as you designed it, does not function properly.

    In any event, keep us posted on what your ultimate decision was and the results.
  • jerry scharf_3
    jerry scharf_3 Member Posts: 419
    not for long

    Tony,

    It's not about the temperature before you start the system up. It's about how well the entire earth area under the floor can transport heat away.

    You state that the earth will be 50F. Once you start rejecting heat into it, it won't stay at 50F. It will rise to the temp of the pipe right at the pipe, and drop off as a factor of thr R vale of the earth. If you have extremely wet soil, this may not be bad, but dry sandy soil would be no good at all. IMO you're taking quite a gamble that the R will stay very low over a fairly large area every moment of the year.

    jerry
  • Wethead7
    Wethead7 Member Posts: 170
    floor heaving

    Try this

    Install a coax heat exchange between the compressor and air
    cooled condenser. Install pex tubing on 9 inch centers{no loop longer than 300 feet) under the floor. Use a small pump anf antifreeze. Wire the pump with the cond fan motor.

    Make sure the antifreeze is tested and adjusted each year.


    Mike
  • Tony_8
    Tony_8 Member Posts: 608
    There's an idea

    I hadn't thought of that, thanks !

    There MUST be some way to keep the floor down, and I'm just trying to use the heat rejected from the freezer to do it.
  • blackoakbob
    blackoakbob Member Posts: 248
    pex under the floor....

    > I hadn't thought of that, thanks !

    >

    > There MUST

    > be some way to keep the floor down, and I'm just

    > trying to use the heat rejected from the freezer

    > to do it.



  • blackoakbob
    blackoakbob Member Posts: 248
    Pex under the floor.....

    I agree with wethead7 with another twist, use a Thermastore or Mueller Free-heater type tank and also add a well in the floor to sense the temp in the center of the floor. The tank will allow you to store some heat and the floor temperature sensor will prevent over heating the floor. Use a glycol solution and don't forget to leave a thermal break from the surrounding floor. You just reminded me of a floor I saw 25 years ago, they just stacked things around the 3 foot heave in the center of the freezer! I don't think I'll ever forget the site of the bare NH3 pipes on the walls and the huge hump in the middle of the room that would rise and fall with the change of seasons. Best Regards
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