Floor Heating Under Freezer


FCB PEX on Floor

These are the floor heating coils in the Freezer, Cooler, Brine (FCB) which I had mentioned installing yesterday. The idea is simply to snake around transferring heat energy so we don’t get perma-frost under the freezer (-10°F to 45°F) or cooler (27°F).

Above the concrete poured over these coils will go a thick layer of insulation, varying with the room type. Above the insulation we’ll pour in place high mass boxes which will be the blast freezer, super cooler and brine room, each thermally isolated from the rest of the building – bottles within bottles. The brine cure room is kept above freezing but might someday be needed as a cooler so it got a set of floor coils too. These tubes all lead to a controller box set in the wall between the cutting room and kitchen.

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27°F might sound cold for a cooler, a refrigerator, but that is still two degrees Farenheight above the freezing temperature of meat (25°F a.k.a. -3.89°C). Because of the naturally occurring amount of salt in the meat it doesn’t freeze until a bit below the freezing point of pure water (32°F). By super-chilling [1, 2, 3, 4, 5] the meat and storing it at 27°F we keep the quality higher and are able to deliver it colder to customers while still keeping it fresh and unfrozen.

The three coils hanging on the wall are measured out to go under the floor of the carcass chiller and then the final cutting room before returning to the controller box. This will cool the deep slab of these rooms without over cooling the final floor layer.

Having the rooms each at a different temperature also allows us to stage the process of freezing meat that is destined for the freezer. The last step in is the blast freezer that will pump the heat out of the meat with high winds and very low temperatures letting us create micro-crystals that mean higher quality when thawed as it reduces the puncturing of cell walls.

Outdoors: 79°F/54°F Sunny
Tiny Cottage: 72°F/67°F

Daily Spark: “May the dragon of life only roast your hot-dogs and never burn your buns!” -Anonymous.

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About Walter Jeffries

Tinker, Tailor…

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8 Responses to Floor Heating Under Freezer

  1. Okay, I’m not following the permafrost under the freezer gig requiring “heating” loops. One just needs insulation under the freezer to prevent permafrost right? Yes, I’m sure I’m missing something obvious here .

    The lower freezing temp of meat (vs. water) was a revelation. In hindsight, yes, obvious, but thanks for the foresight, fantastic!

    • One of the unfortunately common failure modes of commercial freezer systems that has been revealed in failure mode studies is that if there is no air flow gap below some of them. They are constantly pumping heat out of the ground below the freezer which causes trouble from buckling which often first shows up as door frames jamming. Even with enormous amounts of insulation this is true because insulation does not stop heat flow (thus anti-heat e.g., coolth) but rather slows it down. The result is development of perma-frost below the slab which then buckles and breaks the concrete of the foundation. This then necessitates shutting down the facility, tearing up the floors and redoing them properly. In some facilities they put in electric heating cables to pump in heat which is very wasteful.

      To prevent this, in addition to having an air gap and lots of insulation, we have put the PEX tubes in the concrete that is not supposed to freeze. These tubes are down below the insulation layer for the freezer. We are setting it up so we can move the coolth around based on the temperature of the floors to keep the sub-floor above freezing and prevent the perma-frost. This is more energy efficient since we’re not adding heat and then pumping it out with the refrigeration system but are instead simply moving a small change around within the reefer thermos bottle.

      In addition to the red fluid transfer tubes there will be blue 1/2″ PEX tubes going to strategic points in the various slabs so that we can send down probes to monitor the systems which will alert us to any problems in addition to being able to monitor the temperature of the returning fluid.

      We’re very much looking forward to having our super cooler so that we can have roaster pigs hanging and ready, fresh not frozen. I get many people who call during the warm months wanting a roaster pig, “This weekend!” and this will let us serve that market. Normal turn around time is two weeks to a month.

  2. Michael Huston says:

    Very enlightening about the permafrost Walter, I was going to ask the same question as Oliver.
    Is the controller box something you can purchase off the shelf or are you designing that as well? What is the fluid you will use for the heat transfer?

  3. Michael Huston says:

    You do not need to answer the questions in my other comment, I see the answer in your previous post.

    Thanks as always for such a wonderful blog!

    Michael

  4. Aldo Moore says:

    excellent written article, thanks

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