Is electric resistance heating worth the cost?
Q. My utility bills are high and often I’m chilly. I know electric resistance heating is expensive to operate, but I like the idea of infloor heating. Does it only work in tile or can it be used under carpet?
A. In general, electric resistance heating is expensive to use for heating a house. This is why most homes that have all-electric heating use heat pumps which can be several times more energy efficient than resistance heating. Resistance heating is basically a big toaster with a blower.
Electric infloor heating is technically no more efficient than an electric resistance furnace, but, because it improves comfort dramatically, it can be much less expensive to operate.
A house will use several percent less electricity for each degree the thermostat is set lower. With improved comfort from infloor heating, you should be able to lower the thermostat setting and not feel chilly. With infloor heating, you can have a separate computerized thermostat for each room so you can heat a room only when you need it.
Instead of heating the room air, a warm floor radiates heat upward to your body making you feel warmer. When one’s feet are warm, your entire body feels warm. Infloor heating reduces the extent of heat stratification where the hot air from a furnace naturally collects up near the ceiling.
Infloor heating is most efficient in a concrete slab or in a tile floor with high thermal mass, but some types are specifically designed to be used under carpeting, hardwood or laminate flooring. It can actually provide better comfort under carpet or hardwood because their low thermal mass allows the floor temperature to respond faster to the wall thermostat.
In a concrete slab or under a tile floor, electric heating cable is usually laid in a serpentine pattern in the concrete or thinset. For use with carpeting, thin mats or sheets are placed on the floor before the carpeting is laid. The manufacturer can calculate the amount your rooms need. Some of the systems are designed for do-it-yourself installation.
WarmlyYours has a design with thin electric heating cables embedded in a strong fiberglass mesh. This is particularly effective for under hardwood flooring. First check with the hardwood flooring manufacturer about the maximum allowable temperature to avoid excessive drying of the wood.
Another design by Heatizon uses a low-voltage heating mesh. This mesh is only about one-eighth inch thick and is stapled directly to the subflooring. Being a safe low-voltage, installation is relatively easy. WarmlyYours also offers a wafer-thin heating kit that is placed between the pad and the carpet.
The following companies offer electric infloor heating systems: Calorique, (800) 922-9276, www.calorique.com; Emerson, (800) 621-1506, www.emersonindustrial.com; Heatizon, (888) 239-1232, www.heatizon.com; Orbit Radiant Heating, (888) 895-0958, www.orbitrdiantheating.com; Suntouch, (888) 432-8932, www.suntouch.net; and WarmlyYours, (800) 875-5285, www.warmlyyours.com.
Q. My house is only about six months old. The interior side of the band joist feels damp, but I cannot find any leaks from the exterior. Where should I check to find the source of the dampness?
A. You probably do not have a leak in the exterior envelope of your house. If you did, the band joist would be more than just damp and you would likely see a puddle somewhere.
Since your house is new, the moisture you feel on the interior surface is just from excessive humidity inside your house. New building materials often contain a lot of moisture and it can take a year or more to air out. Since the band joist gets cold, you notice the dampness there.
Ÿ Write to James Dulley at 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit dulley.com.