Radiant Floor Heating Systems

"Wet" installations are the oldest form of modern radiant floor heating systems and they work by the cables or tubing being embedded within a solid floor. The tubing or cable can be embedded in a thick concrete foundation slab or in a thin layer of concrete, gypsum, or other material installed on top of a subfloor. If concrete is used and the new floor isn't on solid earth, additional floor support may be necessary due to the added weight. You should consult a professional HVAC engineer to determine the floor's holding capacity for this type of radiant floor heating system.

Due to recent innovations in floor technology, "dry" floors, in which the cables or tubing run in an air space beneath the floor, have been gaining in popularity for radiant floor heating systems. This is because a dry floor is faster and less expensive to build. Because dry floors involve heating an air space; however, the radiant floor heating system of this kind needs to operate at a higher temperature than wet installations.

Some dry installations of radiant floor heating systems call for suspending the tubing or cables underneath the subfloor between the joists. This method requires drilling through the floor joists in order to install the tubing. Reflective insulation must also be installed under the tubes to aim the heat in the air. Tubing or cables can also be installed from above the floor, between two layers of subfloor. In these instances, liquid tubing is often fitted into aluminum diffusers that spread the heat of the water across the floor in order to heat the floor more evenly. The tubing and heat dispersers are secured between furring strips, which carry the weight of the new subfloor and finished floor surface.

A radiant floor heating system has a number of advantages: it is more efficient than baseboard heating and usually more efficient than forced-air heating because no heat is lost through ducts. It can also be advantageous because of the absence of moving air to people with severe allergies. Liquid-based, or hydronic, systems use little electricity. This is a benefit for homes off the power grid or in areas that have high electricity prices. The liquid-based radiant floor heating systems can also be heated with a wide assortment of heat sources, including standard gas- or oil-fired boilers, wood-fired boilers, solar water heaters, or some combination of these energy sources

A hydronic system of heating or cooling involves the transfer of heat by a circulating fluid (as water or vapor) in a closed system of pipes. A hydronic system is the most popular and cost-effective radiant floor heating system for climates that are heating-dominated. A hydronic radiant floor system pumps heated water from a boiler through tubing laid in a pattern underneath the floor. With this type of system the temperature in each room is controlled by regulating the flow of hot water through each tubing loop. This is accomplished by a system of zoning valves or pumps and thermostats. The cost of installing a hydronic radiant floor heating system varies by location, the size of the home, the type of installation, the floor covering, remoteness of the site, and the cost of labor.

Electric radiant floor heating systems are typically only cost-effective when there is a relatively high cost of electricity. Inn this case they should include a significant thermal mass, such as a thick concrete floor. Additionally, the cost of a radiant floor heating system is reasonable only if your electric utility company offers time-of-use rates. Time-of-use rates allow you to heat up the concrete floor during off-peak hours. If the floor's thermal mass is large enough, the heat stored in it will keep the house comfortable for eight to ten hours, without any further electrical input. This is true particularly when daytime temperatures are significantly warmer than nighttime temperatures. Time-of-use applications save a considerable amount of energy dollars compared to heating at peak electric rates during the day. Electric radiant floor heating systems might also make sense if you've put an addition onto your home for which it would be impractical to extend the heating system into the addition.

Because air cannot hold large amounts of heat, air-based radiant floor heating systems are not cost-effective in residential applications, and are seldom installed. Although they can be combined with solar air radiant heating floor systems, those systems suffer from the obvious drawback of only being available in the daytime, when heating loads are generally lower.

If you have a radiant heating system and you are encountring problems, check the following prior to calling your heating service company:

* Is there fuel available for the system? Check your fuel supply?

* Are all of the fuel shut off valves open?

* Check the emergency switch and the service switch.

* Check the circuit breaker or fuse for the heating system.

* Make sure that your thermostat is turned up higher than the room temperature and that "heating" is selected.

* If you have a night setback or "unoccupied" function, make sure that it is inactive.

* Have there been any recent changes made to the home:
a) New floor coverings (rugs,carpeting, etc.).
b) New windows, doors or room additions.

By checking these items before you call for service you may be able to find and solve the problem yourself. Call a professional if the troubleshooting techniques don't work.