The Serenity of Warmth
Electric radiant-floor systems add comfort to any room
By:
Mike Berger
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  (9/10) Cold floors make us cringe when we crawl out of bed and shudder as we step out of the shower. Imagine how great it would be if your home’s floors offered a toasty welcome and helped to heat the house at the same time. No matter what type of floor you have, you can transform it with an electric radiant floor-heating system. Once considered a luxury found only in very expensive homes, radiant-floor systems now come in DIY-friendly kits that are easy to install and affordable. A radiant heating system supplies heat directly to the floor surface, which radiates warmth to the people and objects in the room (see illustration, p. 62). In general, this system is more efficient for delivering heat to its intended location than baseboard or even forced-air heating systems because no heat is lost as it travels through ductwork. And because radiant heating doesn’t rely on blowing large quantities of air, it can benefit people who suffer from allergies. There are two main types of radiant-floor systems: hot-water (hydronic) systems, which route water through a series of tubes that radiate the warmth, and electric systems, which use wires imbedded in large mats or pads to warm the floor. Although both types can be installed by homeowners, electric systems are the most DIY-friendly. Basic installation
A typical electric radiant floor-heating installation starts with preparing the subfloor. Sweep up any debris that might damage the heating pads, and make sure the surface conforms to the requirements of the flooring material you’ll be installing on top of the pads. (We chose a floating floor — by far the easiest type of surface to install over a radiant-floor system.) Before installation, remove the heating pad from the package and attach both lead wires to a high quality digital ohmmeter to measure the resistance. In general, the resistance must be within 10 percent of the manufacturer’s recorded resistance. Once the subfloor has been prepped, lay the heating pads (with heating wires facing up) over the subfloor, allowing a 1-in. gap between the pads and the walls (see Photo 1, at right). Make sure to orient the pads so that their power leads all run in the same direction; then use strips of duct tape to join the pads and to attach the wires to the exposed subfloor (see Photo 2, at right). Cover any remaining exposed subfloor with underlayment recommended by the flooring manufacturer (see Photo 3, at right). To allow room to run the pads’ power wires and the thermostat’s temperature sensor from the floor to the thermostat box, you’ll need to cut away a small section of drywall and notch the wall’s sill plate; then use a fish tape to snake all of the wires up behind the wall and into the electrical box (see Photo 4, at right). When positioning the temperature sensor on the floor pads, be sure to closely follow the manufacturer’s instructions; otherwise the thermostat may not function properly. Next, install the floating floor over the heating pads, following the manufacturer’s instructions. Once the floor has been installed, use an ohmmeter again to check for any damage to the pad by measuring the final electrical resistance of the pads (see Photo 5, at right). If the variance is greater than 10 percent of the manufacturer’s recorded resistance, you may have inadvertently damaged one of the heating pads, and you’ll need to call the manufacturer for instructions on how to isolate the broken wire and repair it. At the thermostat’s electrical box, connect all of the black wires from the individual heating pads to one pigtail and all of the white wires to a second pigtail; then screw the two pigtails to their proper terminals on the thermostat (see Photo 6, at right). Attach the temperature sensor and the main power circuit leads to the thermostat, install the thermostat in the electrical box, activate the circuit and check to make sure that the thermostat is working properly. If you’ve done the job well, the only sweat you’ll be feeling is from the warmth radiating beneath your feet. Proper Planning
An efficient electric radiant-floor system starts with good planning. Consult your local retailer or the manufacturer to determine how many pads you’ll need for the square footage of the room you want to heat and what the power requirements will be. Although in a very small installation it may be possible to draw power for the system from an existing circuit, in most cases you’ll need a dedicated circuit, and depending on local codes, you may need to hire an electrician to install it. (Always consult local code authorities before beginning a project.) Bear in mind that electric radiant floor-heating systems also require the protection of a ground fault circuit interrupter (GFCI), and if you don’t plan to use a thermostat with built-in GFCI protection, your electrician will need to install a special GFCI circuit breaker. Other DIY Applications
Although installing radiant heating pads beneath a floating floor is a relatively easy process, other types of floors have special requirements and installation needs. For example, in a carpeted room you’ll need to use a product specifically designed for this application, such as the Environ II heating system from Warmly Yours. This system is installed between the pad and the carpet and features a unique foil face that reflects heat upward and helps to counteract the insulating properties of carpet that would otherwise block the heat from radiating into the room. If you plan to install a traditional tile floor, you’ll be able to use many of the same products that are available for floating floors, but you’ll need to imbed the heating pads in a layer of thinset mortar. Remember to read the installation instructions carefully, and if you have any questions about what product will work for your situation, consult the manufacturer.
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