RADIANT HEAT is as old as the sun and fire. But ceiling electric radiant heat, popular in areas with cheap electricity in the '50s is an idea being revived and improved.

Last June a new electric radiant heat product became available. The product, with the cumbersome name of Energy Kote Radiant Comfort Heating System, can be used as a primary or auxiliary source of heat in both residential and commercial structures.

As an auxiliary source, radiant heating can be used in combination with any other form of heat, including solar. Radiant heat heats objects, not air, unlike convection heat.

Each Energy Kote panel is one-inch thick. It is made up of three layers: a patented heating element, surrounded on one side by a lightweight fiberglass insulation board and on the other by a textured surface coating.

The heating element itself is made of a sheet of graphite with a copper conductor bonded between two layers of dielectric polyester film. The heating element is then backed with fiberglass insulation, faced with a flameproof surface and framed with lightweight aluminum.

When you plug the panel's junction box into your ceiling, electricity is conducted in the heating element layer of the panel, along the copper conductors and the graphite sheet. The panels come in a variety of sizes and are wired for all voltages. Each unit is controlled by a thermostat.

The main difference between these panels and earlier versions is their weight. The heating elements of the older ones were encased in heavy metal, whereas the Energy Kote panels are surrounded by only lightweight materials.

A qualified electrician or building contractor should do the installation unless the homeowner is very confident of his abilities. The panels could be a fire hazard if installed incorrectly, warned Patricia Watson of TVI Energy Corporation, manufacturer of the panels.

Radiant panels have been marketed in the past by other companies. In the '50s, especially in Tennessee Valley Authority territory, ceiling radiant heat was very popular. But in the Washington area, according to Joanne Barrett, electric and plumbing appliances buyer for Hechinger's, "the earliest ones I remember came in colors and looked like ceiling decorations. I don't think the consumer really knew what to make of them. The earlier panels didn't do very well and the companies that made them stopped their production." See RADIANT, Page 2, Col. 1 Radiant heating panel in the ceiling; photo courtesy Energy Kote. Ceiling Heating: A Radiant Idea --- RADIANT, From Page 1

Among radiant heat panels still on the market are Zell-Aire's glass panel heat and Gold Bond Building Products' Panelectric Heating System--both are UL listed.

Among the benefits of radiant heating panels, according to TVI's Watson: no noise, no moving parts, no odor, no air movement, no drafts, no dust stirred up. One user said, "It's like being under an electric blanket."

"The biggest attraction is the system's instant response time," says Watson. "The system can be turned off during the day when you're at work -- keeping your house or room at a low temperature. Then when you return you can turn the system back on. It heats up in four to five minutes time." The TVI Energy Corp. claims the panels used as auxiliary heat can save 30 to 50 percent over a whole house convection system.

"Every degree you set back your thermostat," says Watson, "saves 3 percent of your heating load."

Michael McGrath, director of technical services at the Edison Electric Institute, explained that heat moves from one place to another in three ways:

Conduction -- as when you touch an ice cube;

Convection -- when heat travels through air or water (similar to an old-fashioned radiator);

Radiation -- heating an object rather than the air. A good example is the heat from a fireplace and the sun.

McGrath points out that with radiant heating, heat is not wasted on the air but goes directly to the object requiring heat -- in other words, you. "With radiant heat, you can be in a 60-degree room and still feel warm." A good example of this, he says is the outdoor "waiting room" at Armand's Chicago Pizzeria in northwest Washington.

The TVI panels come finished in what looks like a white rough stucco, but they can be spray-painted with acrylic paint to match your current decor. The panels can be mounted directly to the ceiling joists, as part of a fiber board panel ceiling, and spray painted. The panels can also be surface mounted on existing ceilings. The whole procedure, says Watson, should take no longer than wiring up a lighting fixture. The mounting, however can be more difficult. A homeowner who recently installed the system said it took two days to mount it to the existing ceiling.

The smallest panel is 2-by-2 feet and costs $80; the largest is 4-by-8 feet and costs $300.

Richard Senechal, a Bethesda architect, was one of TVI's original customers during the test marketing period. He built his four-bedroom three-story house about a year ago, including the panels as his primary source of heat. "I think they're very economical," says Senechal, "although I have no way of telling what I'm saving since this house has never been without the panels. The panels are wonderful from a design point of view--they're light weight and elegant. They're more efficient than the older models of cabled panels, since you have more zone control."

The panels get as hot as 180-190 degrees F, but Watson, as well as Underwriters' Laboratory, say this is not dangerous. Because the panels are out of reach, there is also little problem of accidently touching them.

To find out more about the Energy Kote Radiant Comfort Heating System, call TVI's toll-free number: 800-243-2354. Or call local distributors, Zone Heat Systems, 301-953-7030.

Other Products:

The Panelectric system made by Gold Bond Building Products has been produced for about 15 years, according to John Zale of Gold Bond. Unlike the Energy Kote panels, the panelectric panels have wiring or "radiant heating cables" running throughout each panel. A non-heating lead extends from the back of each panel to connect it to the other panels.

In this system, the panels are meant to become part of the drywall ceiling. Zale said that the Panelectric panels should be installed in a home you are currently building. "Installation after a home is built is a more complicated procedure."

Zale also warns that without sufficient insulation surrounding the panels you will lose a tremendous amount of heat. Like the Energy Kote panels, each room can be separately controlled with a thermostat. Prices run about $275 for panels to heat a 20-by-20-foot room. The local Gold Bond distributor is located at 2301 S. Newkirk Rd. in Baltimore.

Berko Radiant Glass Heating Panels also operate with cables that run throughout each panel. They come in two sizes: 2-by-4 feet for $117.10 or 2-by-6 feet for $156.90 and can be surface mounted or dropped into the ceiling. The panels can be ordered through Maurice Electrical Supply Co., 1134 11th St. NW.

Zell-Aire's glass radiant heat panel is composed of a heating element that is fused onto tempered glass. The glass panel is mounted 3/4 inch in front of the reflector. The fused-on heating element is covered with silicone enamel for corrosion protection. The entire unit is mounted in silicone rubber to eliminate hum and expansion noise.

Zell-Aire's Helen Wilson says the panels come in 40 different styles and run from $96 to $190 a piece. The panels are not sold locally. For details write the Zell-Aire Corp., Reading, Pa., 19603 or call 215-376-5401.