Carpet Over Heated
Floors
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The advantages of energy
efficiency combined with a distinctly comfortable heat
source have made heated floors increasingly popular in many
parts of the country. Often referred to as hydronic or
"radiant-heated" floors, these floor systems have been
popular in Europe for many years. Most systems utilize
low-temperature water of about 80° F to 125° F flowing
through flexible tubing installed beneath the floors. These
systems can be embedded in concrete slabs, lightweight
overpours or in joist cavities.
With a floor heating system, the entire floor works as a
giant radiator. The comfort benefits are immediately obvious
under tile, marble, vinyl and wood flooring; however,
radiant floor heating works equally well under carpeting.
With installations involving carpet and cushion,
consideration must be given to the thermal resistance rating
(R-value) of the carpet and padding.
Manufacturers of
heated floor systems state that less thermally conductive
floors, such as those covered with thick carpets,
particularly with heavy cushions beneath, may require the
use of hotter water. This may preclude the use of
water-to-water geothermal heat pumps, some solar systems,
and some waste heat recovery systems. Regardless, most
homeowners accept some efficiency reduction so that the
additional benefits offered by carpet will be enjoyed. A
not-so-obvious benefit which should be recognized is that
carpet tends to shorten the heating season by providing a
"foot warm" floor rather than a "foot cold" floor as with
hard surface floorings.
Heated floor system
efficiency can be improved by properly selecting carpet and
carpet cushion. Most floor systems manufacturers suggest a
total maximum R-value for carpet and cushion not to exceed
4.0. With heated floors, lower pile carpet is better than
higher pile carpet, and the absence of cushion is preferred.
When cushion is used,
it should be no thicker than 3/8". Cushions specifically
designed for heated floor use are available and should be
considered. Call the Carpet Cushion Council at 610-527-3880
for additional information on cushion selection. |