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Radiant heat w/carpet, hardwood, tile?

Dave_4 Member Posts: 1,405
That is a good question... I hear a consensus to have 2 inches of space below the tubing. This is to allow the non-contact (non conductive) heat from the tubing to spread out laterally and warm the entire cavity for a more even floor temperature. I would hope that you would be using extruded aluminum contact plates at least.

If the top of the insulation is foil for reflectivity, great but I would not count on that as it gets dusty and loses that benefit after a couple of years. I learned that right here on The Wall, a few years ago.

Still, I would leave a couple of inches of air space.

By way of contrast, I can imagine if one sprayed Tiger Foam right onto the sub-floor and covering the tubing. This you can see would isolate the tubing, all but the upward portion in contact with the floor and may even "undercut" the circumference to insulate the tubing itself.

Extreme example, but I think it illustrates the point.

In an ideal world (and with Hot Rod and his inquisitive mind and with his FLIR camera, it is pretty darn close to that), a series of Infra-Red snapshots might better tell the tale than what I am giving as reasonable theory.


  • Cheryl_3
    Cheryl_3 Member Posts: 1
    Radiant heat w/carpet, hardwood, tile?

    We'd like to put radiant heat in our new addition, slab 30x44,(Kit,Dine,Family,entry,M.bath,1/2bath)I had hoped to put tile, hardwood and carpet into different areas. What do I need to know before I make a final decission on floor covering. Our contractor has not worked w/radiant heat and it's not common in our area, yet.
    Any help is apreciated.
    Thank you,
    Cheryl in Baldwin City, KS
  • Weezbo
    Weezbo Member Posts: 6,232
    there are lots of things that come to mind...

    here are three of them. Tile will store heat has a easier task of preforming the same function at lower temp waters and may be a candidate for micro zoning depending on location within the structure ....

    wood by all rights and reason should be acclimated to its environment over time and by degree and its moisture content and the emitters (if radiant floor) moisture content evaluated as to suitability of intended use and that hard wood has various methods and qualities when sawn .

    Carpet comes in a variety of materials with variable insulative qualities, the backing for some carpets is extremely different from others and that having said this one would do well to ascertain the applicabilities as it were for the areas where you intend to use the carpeting....

    *~/:) i make up this stuff as i go along :)

    Sorry its a 10 10 game on the 35
  • Brad White
    Brad White Member Posts: 2,398
    Different Materials = Different Temperatures

    The best way to compensate for different floor materials is different water temperatures, Cheryl.

    When zoning a radiant project, I start with a calculated heat loss (for any project, radiant or not), for each room.

    Then I assess floor coverings or potential floor coverings. Each of these is designated a temperature of water based on that room's heat loss.

    As Weezbo noted, tile can do the work a lot better than wood and better by far than carpet. All will work, you just have to think it through. Ceramic tile can work at water temperatures from 80 to 100 depending on room heat loss. Wood will be higher still and carpet might need 120 degrees plus. Many variables to consider.

    An almost parallel next step is zoning by usage, for example bedrooms separate than day-living spaces. In your case it seems to be mostly day-living and the size, if an open plan, makes this kind of sub-dividing less critical.

    Back to temperature: Each floor and it's covering has it's temperature governed by a manifold with circulator and mixing control. From one water temperature you can mix-down to the several "flavors" you need.

    Each room's heat loss, once the water temperature is established, will be dealt with by variables of tubing spacing, depth of tubing and diameter of tubing. A room with a high heat loss but a ceramic tile finish may take low temperature but at a 6-inch spacing. The same room with the same water temperature but a lesser heat loss might take 8, 10 or 12 inch spacing. All have to be calculated.

    "Tube up" each room individually and group them to their manifolds. At the very least, each room can be "tuned" by adjusting flow rates to the tubing, but temperature is the key variable.

    I would suggest that your contractor get in touch with the Radiant Panel Association and buy their guides and take the correspondent courses. It is a learning curve (you did say it is new to your contractor). Both you and he should "read up" so that you can both make informed decisions.

    Another suggestion is to use a national brand of radiant heating supplies such as Uponor, Viega and Rehau. These fine companies, among others, can generate a drawing and perform design services for a fee absent you having an engineer or contractor do so. The bill of materials generated will go a long way toward your peace of mind.

    One last thing- Insulate, Insulate, Insulate the slab, especially the edges. R-10 at least. Just do it.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • Weezbo
    Weezbo Member Posts: 6,232
    now that my thoughts can get into \"focus\"

    on my way to do a combustion test, check out the materials that may be required ,Monday. get a re-con on my homeowner job..and make it back to play a tourney with the luckiest guy in the world ....

    i would like to suggest that Brad is an engineer, and were i you, if you are unable to find someone in your area who is really into this type of work ,...after looking in Find a professional on the top of this page,and the similar menu at the RPA ...

    looking into finding an individual who espouses, even remotely what Brad is saying , Hire the firm on the spot:)

    Brad is hiding out from his day job doing this work today .:)

    engineers need work also :)
  • sean_26
    sean_26 Member Posts: 22

    brad,question for you.on the staple up with heat tranfer plate . should the insulation be next too the heat tranfer plate or should their be a space,if so how much?
  • sean_26
    sean_26 Member Posts: 22

    brad,question for you.on the staple up with heat tranfer plate . should the insulation be next too the heat tranfer plate or should their be a space,if so how much?
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