Radiant floor heating is an ancient but elegant concept. Years ago the Greeks and Romans realized that heat rises and put the theory to work for them. They heated the floors of their baths with wood fires. Now, 2000 years later, the principle still applies: the best way of warming a room is to heat the floor rather than to try to make heat travel sideways from a fireplace, radiator, baseboard heater or air register. Radiant floor heating is simple. It works by using the floor as a giant radiator. Plastic tubes are laid out on the wood sub- floor and then embedded in a light weight concrete, or in the case of concrete slab-on-grade construction, the tubes are embedded in the concrete. Warm water supplied from a boiler circulates through the network of tubes gently warming the floor. The warm floor then radiates to all objects in the room.