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  1. #14
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
    Posts
    1,269
    Wouldn't running a normal "cold-wall" type chest freezer at -30 degrees just cause the inside of it to get smaller and smaller due to massive ice buildup on the walls, or would it be about the same as a 0 degree freezer? Or were these the kind with a fan inside and auto-defrost?

  2. #15
    Join Date
    Aug 2010
    Posts
    2,613
    What's the relationship between wall temperature and frost build up? I don't think its too bad with chest type as the outside air infiltration is minimal compared to front load type.

    The water removal from contents would be reduced, no? The lower temperature reduces vapor pressure/sublimation rate. This is why its said that ultra cold freezing reduces freezer-burn. Granted, not sure how effective this is at -30F

  3. #16
    Join Date
    Aug 2010
    Posts
    2,613
    I'm still wanting to do this, but I think the biggest burden is the capillary tube if it has to be changed. Its encased in the foam.

  4. #17
    Join Date
    Jun 2013
    Location
    N. Canada
    Posts
    395

    R134A chest freezers at -40

    Yes, I've designed hospital plasma freezers (-35 holding, I believe) out of household chest freezers.
    But my refrigerant of choice was R411B. They would peg the -40 test thermometers.
    We had the advantage of "no-break" hospital AC and controlled 72f ambient.
    I did these in 1998 and one is still operating in our nearest city hospital, only repair being the aux fan.

    I'm north on the trapline now, so my other mods are not at hand.

  5. #18
    Join Date
    Jun 2013
    Location
    N. Canada
    Posts
    395
    Quote Originally Posted by ICanHas View Post
    I'm still wanting to do this, but I think the biggest burden is the capillary tube if it has to be changed. Its encased in the foam.
    ICan, I'm sure you would be extending the cap tube, which is no problem.

  6. #19
    Join Date
    Jan 2008
    Location
    LEHIGH VALLEY, PA
    Posts
    161
    used to do this all the time , standard chest freezer , remove compressor and thermostat . fit r404a low back pressure compressor , danfoss oil seperator , add an extra condenser to the rear of the cabinet , thermostat and thermometor , the original air cooled condenser and condenser fan motor were retained , no cap tube alteration , they where sold as -40 c/f. , esta or elcold where the brands at thetime .
    they were a very big seller .

  7. #20
    Quote Originally Posted by COOLJIM View Post
    used to do this all the time , standard chest freezer , remove compressor and thermostat . fit r404a low back pressure compressor , danfoss oil seperator , add an extra condenser to the rear of the cabinet , thermostat and thermometor , the original air cooled condenser and condenser fan motor were retained , no cap tube alteration , they where sold as -40 c/f. , esta or elcold where the brands at thetime .
    they were a very big seller .
    mmkkkk

  8. #21
    sorry about that cool jim could you elaborate more on that converstion do you have pics you can post? how did you fit all that equipment in a standard freezer cabinet how did you attach the condenser this peaks my intrest

  9. #22
    Join Date
    Jan 2008
    Location
    LEHIGH VALLEY, PA
    Posts
    161
    the unit compartment had space enough the models we worked on already an air cooled condenser , which we retained the new compressor slightly larger than the original no poblem there , no copmrpressor valves just swet type, the danfoss oub oil sep , had right angle fittings and were sweat . the condenser we made our selves , sheetsteel folded wth a flange and i think 2 in height of the back of the freezer with 1/4 inch pipe poke welded with clips we made , spray painted black , screwed to the back of the freezer no existing cabinet piping to be concerned with . we sold off the removed compressors and stats easily .jim

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