Radiant Floor Heating Definitions
Radiant floor heat envelops a room like a warm blanket. Winter morning trips to the shower are cozy and inviting when your toes are not freezing. Heat radiates from beneath the surface of the floor, turning the floor into a warm, subtle radiator.
Types of radiant floor heat
There are different types of heated floors. Hydronic floors use liquid--such as water or glycol--circulated through pipes or tubing, just beneath the floor. Air-heated floors circulate hot air to warm the surface. Electric floors use an electric element, like a giant toaster strip.
Concrete being laid over PEX tubing that will circulate glycol through the finished floor.
Hydronic (water or glycol)
Poured concrete usually goes into new construction, but it can be put over top of an existing sub-floor as long as you don't mind raising the floor a few inches. Before pouring the concrete, an installer strings out a flexible tube and attaches it to reinforcing wire mesh or re-bar using zip ties. Then he pours the concrete.
When the floor dries and cures, a plumber connects the tubing to a boiler or hot water tank. The most efficient method is to use a solar hot water system. You can stain or paint the concrete, or cover it with tile, wood or carpet. When the concrete heats up, it becomes a big thermal mass and can radiate heat long after the heating element is off.
Another kind of hydronic heat "sandwiches" the radiant floor tubing between plywood sheets and lays this on top of the sub-floor, or attaches the tubing directly under the finished floor or sub-floor.
One of the easiest ways to add radiant heat to an existing floor is to lay down an electric floor mat on top of your existing sub-floor. An electrician makes the electrical connection, often adding a thermostat with a heat sensor. You can lay whatever type of floor you want to on top of it. The installer will use tile glue to secure the mat if you're going to put tile over it, so you have to specify what type of flooring you will use before the radiant floor mat goes in.
While easier and therefore cheaper to install, electric floors are usually much more expensive to run because of the high cost of electricity. They may be better suited to small rooms, or coupled with solar-electric, or photovoltaic, systems and installed in rooms that are only used during the day.
Some electric systems lay a conductive element into a concrete floor, like the hydronic ones, and because the concrete stores heat, they are more effective than mats placed on top of the sub-floor. However, if you're going to pour a concrete floor, it makes more sense to use a more efficient hydronic system to heat it.
Air heated floors
These floors heat an airspace beneath the floor. Air does not store heat, so pumping hot air through a floor is a very inefficient way to heat a space. Air heated floors, according to the U.S. Department of Energy, are not cost-effective for residential use. They are not recommended for homes, especially since there are better options.
Can you do it yourself?
Electric radiant floor heat mats are sold at home improvement centers, as are many of the components needed for hydronic systems. Whether you should try to install such a system yourself depends on your skill level and your local building code requirements.