How Does Radiant Floor Heating Work?
Think of how nice it feels to walk on a sandy beach that's been soaking up the rays of the sun all day. Even at night, when the air is cool and the sun has set, the sand will continue to emanate warmth.
Like sand, concrete is an ideal carrier of radiant heat because of its inherent thermal mass. (Click here to read more about thermal mass). As warm water circulates through the tubing (or as electricity warms the heating elements), the concrete flooring turns into an efficient, inconspicuous radiator. Typically, radiant heating systems warm floors to temperatures of 75 to 80 degrees F. The warm surface then slowly radiates heat upward into the living space, rather than blowing around the heated air. This natural heat transfer is both more comfortable and energy efficient.
For concrete floor radiant heating systems, the warm-water tubing or electric heating elements can either be embedded within the slab-on-grade (anywhere from the bottom of the slab to within 2 inches of the surface, depending on the design and installation technique) or fastened to the top of a concrete subfloor and then covered with an overlay. (These diagrams, from the Radiant Panel Association, show some typical installations.) Radiant heating can also be installed in thin concrete slabs placed over plywood, with a layer of decorative concrete placed on top (see One Contractor's Method for Installing Radiant Heat).
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