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slab on grade radiant heat is anti-freeze needed?

this can be a interesting subject. Let me start by saying that if you use all the right install materials 2" styro in floor and at least 1" all around the perimeter you should NOT have a problem. Glycol, whether its Dowtherm or Cryotec will require good systen cleanliness and annual maintance using a spectroscope not the test strips.
I avoid using it because of the maintanence it. People really think its aone time add it and forget it, its not.Glycol is harder to pump, will gum up air scoops, and depending on the design will effect your heat output.Can you tell I don't like it at all. As far as the power outage is concerned the slab would take days not hour to cool to such a point that would be a freeze issue.
I'm sure others will have better imput. kpc


  • SM
    SM Member Posts: 37
    Will I need anti-freeze? Should I be concerned?

    I have a guy who wants to put radiant heat in a 26 x 68 garage/workshop. There are going to be three bays and three zones. On will be his workshop that he will keep 60-65 the other two will be a garage and storage. He is saying he will keep 45-50. Should I be considering anti-freeze? I in northern Ohio and the design temp is 1F. I am not concerned about power outages, although I maybe I should be. I have lived here 30+ years and can not recall the power being out more than a couple of hours at a time. I am concerned about the pipe on the perimeter of the building during the off cycle. Unless I went with a injection type setup and ran the loop pump for each zone all the time and cycled the injection pump off the t'stat. Should I be concerned? If so what anti-freeze should I consider (name brand). And what does the anti freeze do to my specific heat?

  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083

    took the words out of my mouth! Insulate well, consider pump cycling. A ill maintained glycol system ( and 99% of them are) will kill a hydronic system in short order. Avoid it any way you can.

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  • hr
    hr Member Posts: 6,106
    Kinda like an

    insurance policy. Hard to know how much protection is enough. If you travel a lot in the winter, and the shop is left un attended for long periods, during freezing temperatures, it may be a wise investment.

    A good brand, properly installed and cared for, in a tight system should last for years.

    hot rod

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  • Biro
    Biro Member Posts: 8

    Regarding power outages, what if... you put a normally open soleniod just beyond the return manifold and had it dump out just a trickle of water into the drain in the event of a power outage. Power fails, solenoid opens, water flows, no freeze up. Could that work?
  • Earthfire
    Earthfire Member Posts: 543
    winter startup

    how do you start a new cured 20 degree slab this time of year not using glycol ??
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