Radiant heating systems supply heat directly to the floor to help people in a room stay warm. This type of system works by delivering warmth via infrared radiation, so it's often called radiant floor heating.
Radiant heating has a number of benefits. The efficiency of radiant heating is higher than baseboard or forced air systems, as it eliminates duct losses. Many people prefer radiant heat because it doesn't distribute allergens as forced-air systems do. Hydronic (liquid-based) systems use little electricity and can use many types of energy sources, such as standard gas boilers, wood boilers, solar water heaters, or even combinations of those.
Radiant floor heating depends on convection, the natural heating of air within a room. This is why radiant floor heating is different from radiant panels in walls and ceilings. The following sections discuss these two separately.
Radiant Floor Heat
Radiant heating is a method of heating that doesn’t rely on circulating air via ducts and vents or a furnace.
There are three main types of radiant heat -- radiant air floors, electric radiant floors, and hydronic radiant floors.
radiant floor systems. There are two different installation types. Wet installations involve a concrete slab or lightweight concrete over a wooden subfloor and dry installations use the flooring itself as the heat conductor.
Radiant floor heating, generated by electricity or from the heat of a fire or wood, can be a cost-effective choice to keep your feet warm.
Radiant floor heating is not cost-effective in residential applications and rarely installed. Although they can be combined with solar air heating systems, those systems suffer from the obvious drawback of only producing heat during the day, when heating loads are generally lower. The inefficiency of trying to heat a home with a conventional furnace by pumping air through the floors overnight outweighs the benefits of using solar heat during the day. Some early solar air heating systems used rocks as a heat-storage medium (see solar air heating systems), but this approach is not recommended.
Electric Radiant Floor
Electrical radiant heating systems typically consist of a network of electric power cables built into the floor. Systems that feature electrical matting mounted on a concrete or plywood base below a floor covering such as tile are also available.
Unfortunately, because electricity is relatively expensive the radiant floors are only cost-effective with a significant thermal mass such as a thick concrete floor. This can be achieved by charging the concrete floor during off-peak hours with heat. If it's large enough, this will keep your house comfortable for 8-10 hours without any further input of electrical energy during daytime hours. That saves a lot of money compared to heating up at peak rates when it's day time outside.
Electric radiant floors may not be appropriate for homes that are adding new space, since the heating system would need to be extended into the new area. However, mini-split heat pumps could also work in this case. These systems operate more efficiently and have the added benefit of providing cooling.
THERMAL FLOOR SYSTEMS
Hydronic floor heating systems are the most popular and cost-effective system in heating-dominated climates. This type of radiant heat system operates on hot water that is heated by a boiler, then circulated through heated tubing under the floor. You can control room temperatures by varying the flow of hot water to each tubing loop with a valve or pump, and then setting the temperature with a thermostat. Installing a hydronic floor heating system will vary depending on where you are located and how much work needs to be done, but is usually more affordable than installing electric radiant floors.
TYPES OF SERVICES
No matter what the method of installation is, electric or hydronic systems for heating floors are similar.
Wet installations make use of cable or tubing to install the radiant floor system. The tubing or cable is embedded in either a thick concrete slab foundation that's common in slab ranch-style homes, or it may be installed on top of a thin layer of concrete, gypsum, or other material that's been laid down on top of a subfloor. If concrete is used and the new floor isn't on solid earth, additional floor support may be needed because of the added weight. You should consult an engineer to find out if your floor can support this kind of installation.
Thick concrete slabs are great for storing sunlight for solar heating systems because these materials have a slow thermal response time. The downside to thick slabs is their inability to react quickly, which means it's difficult or impossible to maintain a temperature inside depending on if you're using night setbacks or daytime setbacks. Most experts recommend maintaining a constant temperature in homes with these types of heating systems.
Modern flooring is improving, and as a result, so-called "dry" floors are gaining popularity. It's much faster and less expensive to build a dry floor than it is to build a wet one. One downside to this innovative technology is that the radiant heating system needs to operate at a higher temperature.
In some cases, installation may involve suspending the tubing or cables under the subfloor between the joists. This usually requires drilling through the floor joists in order to run the tubing. Reflective insulation must also be installed under the tubes in order to direct heat upward. Tubing or cables may also be installed from above the floor, between two layers of subfloor. When this happens, liquid tubing is often fitted into aluminum diffusers that spread out the water's heat across your floor to heat it more evenly. The tubing and diffusers are secured between furring strips, which carry weight of your new subfloor and finished floor surface.
Improving upon the idea of plywood subfloor material, at least one company has created a floor made of tubing grooves and aluminum heat diffuser plates built into it. This allows for the use of half as much tubing or cabling, since the floor's ability to dissipate heat is improved compared to more traditional dry or wet floors.
Ceramic tile is the best floor covering for radiant floor heating. Tile carries heat well, which means it will conduct warmth faster and add extra thermal storage. Other floor coverings can be used as well, but covering your room with anything that insulates the floor from the rest of the room will cause your system to lose efficiency.
If you want carpeting, use carpet that is thin and has a lot of padding. Install as little carpeting as possible in any rooms with floor covering; these spaces need to be heated separately to compensate for the floor covering. Wood floors should be laminated instead of solid to reduce the possibility of shrinking or cracking from the drying effects created by heating these types of surfaces.
Wall- or ceiling-mounted radiant panels typically consist of aluminum and can be heated with either electricity or tubing that carries hot water. However, it's important to remember that the latter produces concerns about leakage in wall- or ceiling-mounted systems. Despite this common drawback, most commercially available radiant panels for homes are electrically heated.
Radiant panels are often used to provide heating to a room where the primary heating system is not effective. When extending the heating system in your home is not an option, they can provide supplemental heat.
Radiant panels have the quickest response time of any heating technology, which can result in savings compared with other systems when rooms are infrequently occupied. When entering a room, the occupant can punch up the heat setting and be comfortable within minutes. As with any heating system, set the thermostat to a minimum temperature that will prevent pipes from freezing.
Radiant heating panels work by warming objects they are pointed at, so you'll be most comfortable if you're close to the panel. Some people prefer ceiling-mounted systems because they feel like the panels heat the top of their head and shoulders more than the rest of their body.