About Radiant Heating

Radiant heating systems warm a home by supplying heat directly to the floor or to panels located in the walls or ceiling of a house. Radiant heat systems work by transferring heat from a hot surface to objects in the room, including people, by means of heat radiation, also known as infrared radiation. You experience radiant heating every time you cook on a stovetop or oven and the heat of the stove or over warms the kitchen. However, despite the name, radiant heating, these systems depend heavily on convection, which is the natural circulation of heat within a room created by heat rising from the floor.

The three types of radiant floor heat are (1) radiant air floors, which uses hot air as the heat-carrying medium;(2) electric radiant floors; and (3) hydronic or hot water radiant floors. Each of these three types can be further divided by how they are installed. Those, which use concrete slab flooring or lightweight concrete on top of a wooden subfloor for their thermal mass, are known as "wet installations." Where as the types of radiant floor heat, which sandwiches the radiant floor tubing between two layers of plywood or where the tubing is attached under the finished floor or subfloor is called "dry installations."

Air-Heated Radiant Floors:

Air-heated radiant systems are the least popular type of radiant heating and are seldom installed. This is because air cannot and does not hold large amounts of heat. Therefore, the radiant air floors are not cost-effective for residential or commercial use. However, some installations did combine these systems with solar air heating systems, which also suffer from the same drawbacks plus have the added disadvantage of being available daytime use only. It was because of these draw backs that other forms of heating mediums were devised.

Electric Radiant Floors:

Electric radiant floors generally consist of electric cables that are built into or under the floor. Most systems feature electrically conductive plastic mats, which are mounted to the subfloor and under the either hardwood, tile, carpet, or other floor covering.

Electric radiant floors are more cost-effective if they include a thick concrete slab for their thermal mass. When the thermal mass is large enough, it is possible to keep a home comfortable for up to eight to ten hours, which enables the homeowner to save considerable on their energy bills.

Electric radiant floors are also practical for additions onto homes, in that they are easier to install than having to run extra ductwork. However, before making any final decisions, you should examine other options including ones, which also provide cooling options.

Hydronic Radiant Floors:

Hydronic systems are by far the most popular radiant heating systems as well as the most cost-effective system for heating-dominated climates. Hydronic radiant floor systems, work by pumping heated water from a boiler through tubing, which has been installed on top of the subfloor and underneath the floor covering. In some systems, regulating the flow of hot water through each tubing loop controls the temperature in each room. This is accomplished by a system of zoning valves or pumps and thermostats. The size of the home, as well as the location will determine the price of installing a hydronic radiant floor. Other factors that contribute to the price of labor include the type of installation, the type of floor covering, and the location of the site.

Types of Floor Installations:

The installation of electric and hydronic radiant systems in floors are similar. Wet installation involves the embedding of the cables/ tubing into the solid floor. The cables/ tubing are usually embedded into a thick concrete foundation slab or layered between thin layers of concrete, gypsum, or other sub-flooring material and flooring material. For home with basements, crawlspaces, should consult a professional engineer to determine the floor's carrying capacity.

Thick concrete slab systems provide high heat capacity, however, thick slabs do have a slow thermal response time, which makes planning temperature setbacks nearly impossible. Therefore, it is recommended setting a constant temperature for these heating systems.

Recent developments in floor technology have lead to, dry floors. With dry floors, the cables/ tubing runs through an air space beneath the floor. Dry floors are increasing in popularity, simply because they are faster and less expensive to install. However, the main draw back with dry floors is the fact that they involve heating an air space, which means that the radiant heating system must operate at an increased temperature.

The installation of some dry floors involves suspending the tubing/ cables beneath the subfloor between the joists. However, this method generally requires the floor joist to be drilled through in order for the tubing/cables to be installed. In addition, reflective insulation must be installed below the tubes/ cables to direct the heat upward. Cables/ tubing can also be installed by sandwiching them between two layers of subfloor. When the cables/ tubing is install using this method, the tubing is often fitted into aluminum diffusers, which disperses the heat of the water over the floor providing a more evenly heated floor. The cable/tubing and diffusers are held between furring strips that support the weight of both the subfloor and finished floor covering.

Floor Coverings:

Radiant heating systems can be used with nearly any type of floor covering. However, ceramic tile is the most common and most effective for radiant floor heating. This is because of how well it conducts heat from the floor. Other common floor coverings include vinyl/ linoleum, carpeting, and wood. However, keep in mind that floor coverings that help to insulate, such as carpeting, will decrease the efficiency of the system.

If you have your heart set on carpeting, then install a thin carpet and dense padding. If you plan to have various floor coverings through out your home, then in rooms where you plan to have carpeting, you should have separate tubing loops installed so that the system will heat these areas more efficiently. This is because the heated water under the carpeted areas will need to be hotter in order to compensate for the carpeting. If you are installing wood flooring, laminated wood flooring is better to use over radiant heating instead of solid wood because laminated flooring does not shrink and expand due to the heat.

There is a lot to consider when installing radiant heating, however, nothing feels as nice and cozy as walking across warm floors in the winter.

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