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Sand over radiant?

Big Ed_4
Big Ed_4 Member Posts: 2,697
Do you find radiant heat wood floor tadder the wood over time.
I have enough experience to know , that I dont know it all


  • Luke V.
    Luke V. Member Posts: 2
    Sand Over Radiant?

    I have a customer who wants to put an 1-1/2" layer of sand in between the sleepers over the top of my tubing. Customer does not want gypcrete. They are putting 3/4" wood flooring over the top. Any ideas on reccomended installation of the sand. Does it need felt paper over the top? What kind of sand? Any ideas would be of great help!
    Rocky Mntn Plg. & Htg.
  • mikea23
    mikea23 Member Posts: 224

    Dry sand does not conduct heat very well.I had a customer do this some years back and it worked but supply temps are kinda high. You also have to consider pipe expansion.

    I never did this but with Geothermal the best conductor is clay I always wanted to try it with radiant. I think it would work great and compacted it would help with expansion.

    Mike A
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    It's a mess

    and it doesnt work very well. You also have to very careful not to get sand in between pieces of wood where it can make noises. There are better options. Those options depend on the heat loss. If the heat loss is low you could just leave air space. If it's high use plates. Watts Htwy suggests putting flashing on top of the sub floor, and in under the hardwood, to spread the heat and have the tubing touching the sub floor from beneath. I havent done that yet but it makes sense to me. Good luck. WW

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  • hot_rod
    hot_rod Member Posts: 21,856
    at least add some portland to it

    dry sand is a poor conductor, has terrible consolidation, and has been know to harbor bugs. especially when warmed :)

    If the wood is not in contact with the sand you lose the best heat transfer, conduction!

    It may work to some degree under concrete where it touches the emitter (slab)

    Adding some cement to the sand would keep it where you want it, increase the heat transfer from the tube and into the flooring where you want the heat.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Does

    pea gravel or some similar small rock or stone product trasfer heat ? I think I saw a Bob Vila show where they had a rock floor in a sun room that picked up alot of heat from the sun and released it at night . Thinking about it , not the best choice if the tubing rubs against the rocks while expanding and contracting .

    Levittown was built with radiant pipe sandwiched between sand and concrete . Mostly in the upper layer of sand though , with no insulation underneath . But it worked great ...... while they lasted .
  • EJW_3
    EJW_3 Member Posts: 69

    How about 3/4" rigid foam between them, then tubing and subfloor. I have done this with onyx and it worked well.
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