Radiant floor heating systems are used to disperse heat through a house or office building by forcing a heated medium beneath the floor paneling. There are three main types of radiant heating: electric, air, and liquid. By heating the chosen medium and pumping it through pipes, heat rises from the floor in even dispersal.
A radiant floor system can be built either using a large thermal mass as an insulator--such as a slab of concrete with piping running through it--or by placing the piping directly beneath the wooden or linoleum floor. If placing carpet over the floor, it is important to use as thin a carpet as possible, since the insulating properties of the carpet will keep the radiant heat from drifting upwards.
Electric floor systems are popular only in regions where electricity is inexpensive, or where an electricity provider offers off-peak rates. When using electrical heating, it is almost always advisable to use a large thermal mass such as concrete, to ensure you can take advantage of the most beneficial electricity rates and build up heat during that time to last during the more expensive hours.
Air heating systems are unpopular amongst the radiant floor heating community because of their inability to retain much heat over time. They are used only in situations where little heat is needed--for most residential uses they are simply too inefficient, (barring milder regions of the country).
Liquid is the most common medium in modern radiant floor heating systems. Also known as hydronic systems, they can use anything from oil to water as their heat-bearing liquid. A central boiler heats the liquid and then pumps it through the piping in the house. Most radiant floor heating systems have a number of zones of piping, allowing heat dispersal throughout the house to be regulated by sealing off certain zones and leaving others open for the flow of liquid.
Any type of floor may be used with a radiant floor heating system, including hardwood, linoleum, concrete slab, tile, or vinyl. Ceramic tile is by far the most popular, because it passes the heat easily, is aesthetically pleasing, provides substantial thermal mass, and many people enjoy the feel of warm tile on their bare feet. When using wood, it is a good idea to treat the wood to reduce cracking or warping.
Radiant floor heating has been in use since the days of the Roman Empire when they made use of an air heating system. In the 1930s Frank Lloyd Wright was the first prominent architect to widely use radiant floor systems, choosing hydronics. Since then, many architects have begun integrating radiant systems into the floors of their houses. In addition to being slightly more energy efficient than traditional forced-air systems, radiant floor heating systems have the added benefits of having no aesthetic marker such as ducts, they introduce no outside dust or particulate matter into the house, and they are completely silent. This has made it a favorite in recent years, with more and more homeowners turning to radiant floor heating for their climate control needs.