Basement floors are made of concrete and are called "slabs" or "concrete slabs." A concrete slab is heated by placing flexible tubes on the gravel fill and looping them in a circuit. Concrete is then poured over the flexible tubes to make the basement floor.
The flexible tubes are filled with water or an anti-freeze combination. This water is then heated by a traditional boiler, water heater or solar collector. The flexible tubes heat the slab which then radiates the heat from the slab to the living area of the basement.
Radiant heat is energy given off by a warm surface. This energy is in the form of Infra-red (IR) radiation. IR radiation moves in every direction, not just up like warm air does. An excellent example of radiant heating is the feeling of heat given off by a camp fire that has died down to just hot coals. Not only do you feel heat above the coals, but also to the side. Radiant heating moves in all directions equally, not just up like heated air. This gives extremely even heating in an area with no cold spots to worry about.
The vast majority of basement floor radiant heat systems are installed during the construction process of a new home. This is the most economical installation since the cost of the basement floor slab has already been calculated in the cost of the building. It is a simple matter to add the radiant floor heating system. The radiant floor heating system can heat an area on its own or in conjunction with a traditional forced air, baseboard heat or wood stove.
It is possible to install a concrete slab radiant heating system over an existing concert slab. The flexible tubing is installed over the top of the existing basement floor and a new layer of concrete or other cementious product is then poured over it.