Turn up the Heat with Electric Radiant Heat

by Marilyn Thurau

This following article appeared in All Points Bulletin (January 2000), a newsletter for the home-remodeling, repair and real estate industries. This copyrighted article is reprinted with permission. Call 415-641-1006 for newsletter subscription requests.

irst came the sun, then fire pits and fireplaces. Later, there were ceramic or cast iron stoves. Each had one thing in common -- it produced radiant heat, a heat that warms the body without warming the air in between. Unfortunately, each of these heat sources warmed only the side of the body facing the fire. Today's radiant systems are designed to warm the entire body from all sides. And they're as varied as the needs of the homeowner, whether the home is small and compact or full of rooms with high ceilings and lots of windows.

In Hot Water

Modern radiant heat came into being when builders used pipe assemblies to carry water heated by a boiler to a radiator such as the old cast iron units still in use in older Bay Area apartments, condos, and homes. This hot-water-passing-through-pipes system -- also known as hydronics -- is what most consumers picture today when they hear the phrase "radiant heat." Hydronic components from the '50s have been prone to fail.

But today, they've been greatly improved through a number of tried-and-tested innovations: use of continuous plastic tubing instead of metal piping; superefficient heat generators; and an assortment of sophisticated controls. Heat-conducting tubing can be installed in and under floors, in walls, or above ceilings. It can even be designed to terminate in designer-styled radiators. A well-executed hydronic system is efficient, clean, and quiet, and a popular choice for homes and commercial spaces.

Down to the Wire

But what about remodeling projects where only one room is remodeled -- surely those can be difficult to heat? For instance, the floor level can't be raised to embed heating pipes, or there's no place for the additional water heater that the new room might need. Enter electric radiant! Instead of using a boiler and hot water to hydronically convey heat throughout the home, the electric radiant heat system uses wires that are connected to your home's electric service system. In this case, the warmth generator may be any of four types:

• Long, heavily insulated cable; used in concrete slabs when rated at 240 volts. These low-profile cables can be fastened directly to the subfloor and require only .125 inch to .25 inch of thinset cement adhesive for 120-volt systems.

• Insulated wire mat system (low voltage and made for 120-volt systems); the element is held in place by a nonwoven fabric or plastic mesh and can also be attached directly to the subfloor with thinset. Low-voltage-system mats look like bronze window screens and require a transformer to reduce house current to low voltage.

• Printed circuit; another product that uses thin film technology. Suitable for ceiling or underfloor installation; available for 120- and 240-volt systems.

• Aluminized panel; self-contained units with a textured surface and insulated back, which are fastened to the ceiling.

Fortunately, each of these radiant heat generator systems has a "best-use" scenario and can be placed in a variety of building locations: on or in the ceiling, on the floor, or under the floor.

Controlling the Purse Strings

Controls for these systems vary from the basic on-off switch to air- or floor-sensing thermostats. They can also be connected to a sophisticated energy management program if the ultimate in convenience and energy savings is desired. The question of operating cost always comes up when electric heat is discussed. The advantage of radiant electric heat is that you choose only those areas or rooms you'd like to heat, not the entire building.

Don't activate the furnace, just turn your radiant heat thermostat up to the desired temperature. For instance, you can warm your bathroom floor (along with the bottom of your feet) whenever you want, whether early in the morning or anytime in the evening through the use of floor sensing thermostats and timers -- without turning on -the central heating system. The majority of homeowners find that the comfort of warm radiant floors far outweighs their operating costs.

The Heat of the Moment

Who uses electric radiant systems? I received a call from a couple in Marin who had recently finished a stunning bathroom remodel, complete with a rich marble tile floor. Dan and Sally's problem was that their beautiful floor was too cold to walk on. The solution 1 proposed was to install a thin film product under the bathroom's plywood subfloor. At the hands of KCO-TV's "House Doctor" host, an electric radiant heat product was stapled to the underfloor joists and then connected to a 120-volt circuit. The House Doctor next replaced the thermal insulation beneath the new radiant warming system. With a thermostatic temperature control, Dan and Sally can fully enjoy their new bathroom, walking barefoot on the warm marble floor.

Keep a Cool Head and Warm Socks

Another client who had already installed a floor-warming system in his kitchen realized that a section of his downtown office space was too cold for comfort. With the help of an aluminized panel system and a radiant sensing thermostat, the office is now comfortable and has lost its clammy feel.

A contractor whose lower-level TV room was uncomfortably cold installed a mat system that was laid between the carpet and pad under the sofa. The warmed area keeps his feet warm. A timer turns the heat on prior to television viewing time and off when that period is over.

Comfort Zone

If your home or office has a cold spot or chilly space that no one wants to inhabit, an electric radiant system may be the solution. You want to be comfortable, and you should have the ability to create a warm and cozy setting where you live and work.

Electric radiant heat is an affordable system that can be installed virtually anywhere. If you're unsure of its abilities and restrictions, ask questions and do your homework.

Given a choice, people who have experienced living with radiant heat love it -- they seldom if ever return to conventional furnace and boiler systems.