Friday, June 23, 2006
Radiant heat: a way to warm the tootsies
By Ann Robinson and Annie Vernon
We've all had the experience. You wake up early and stumble to the shower. The carpeted bedroom and hallway are fine, but one step on the tile bathroom floor and you shock your tootsies wide awake. That floor is cold!
It may be a welcome feeling in summer, but it's torture in winter.
We are seeing more and more homeowners choose an alternative method of heating their homes that not only saves their feet from cold tile, but provides several other benefits too. The method is radiant heating.
The concept is not new. Radiant energy transfer is caused by a warm surface giving up its heat to a cooler surface. The Romans channeled hot air under the floors of their villas, and the Koreans channeled hot flue gases under their floors. You might also recall seeing radiators in older homes. Radiant heat went out of style with the advent of the forced air furnace, but it has lately made a comeback.
Radiant heat can be distributed from panels, baseboards, or flooring, but flooring is most popular. The most common type of radiant heating is hydronic. This system uses a boiler to heat a fluid (often water), which travels through a series of pipes and transfers heat into a space. Some of the early floor pipes were made of copper or steel tubing, but they were vulnerable to corrosion and leaking. The material of choice today is PEX (cross-linked polyethylene), which is more reliable and flexible.
Another form of radiant flooring uses electricity. Electric cables are used instead of pipes to conduct heat through or under flooring material. This system can be installed adding only about 1/8 inch to the floor height, which makes it useful in some remodeling situations. Electric systems also have a faster response time than hydronic systems and are easier and less expensive to install. But an electric floor is usually used in a limited area to enhance comfort rather than provide primary heating.
There are several advantages to radiant heating. It is the most comfortable form of heat because it heats objects rather than air, providing a steady, even heat. Unlike forced air, floors rather than ceilings are the warmest parts of the room — because "hot air" rises but "heat" can go any direction. Because it warms your body instead of the air, people generally feel comfortable at a lower temperature, which means you can set the thermostat lower and save money. And because there is no fan, the system is whisper quiet with no drafts moving dust and germs around your home.
It is important to note that a home that requires cooling will need a separate cooling system installed. In terms of initial installation, forced air is the least expensive, with electric radiant heat next. (Compare a typical bathroom: Initial cost for forced air is approximately $200-$400 and electric radiant heat is $400-$800.) A complete hydronic system with a boiler has the greatest initial cost, averaging about $4 to $6 per square foot. However, some hydronic systems are now available for smaller areas (1,000 square feet or less) that use a domestic water heater rather than a boiler.
If you have a little flexibility in your budget, radiant heat is a great way to heat your house and keep your feet warm and your head cool. As always, we welcome your home architect design questions at firstname.lastname@example.org.