Carpet Over Heated Floors
 

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.

Floor Covering Considerations
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 203-637-1312 for additional information on cushion selection.

Article Courtesy of The Carpet and Rug Institute (CRI)