Installing a Radiant Floor Heat System

underfloor heating construction

Radiant floor heat works on the principle of thermal radiation. This is explained scientifically by the fact that electromagnetic radiation is emitted from the surface of a heated object. A simple example of thermal radiation is the sun, or a light bulb. This is the principle used in a typical electric baseboard heater. Electricity is utilized to heat the elements of the baseboard heater, and the heat is distributed throughout the room through thermal radiation.

Radiant floor heat works on this same principle. The main difference between the standard baseboard heater and radiant floor heat is that the panels are placed in the flooring of the home, and radiate the heat upwards towards the ceiling. Electrical cables, or tubing charged with hot water, are placed in the flooring of a home, and the energy supplied to these heating elements causes heat to be generated, and thus warms the home. Depending on the installation, the radiant heat system's thermostat can be set 4-8 degrees cooler than that of a a typical forced air system and still accomplish the same level of comfort. This can amount to a great deal of savings over the typical heating period in many parts of the northern United States.

Installation of a radiant floor heating system is accomplished by different methods, depending on whether you are installing the radiant floor heating system in new construction, or are adding radiant heat to an existing home. Methods of installation may vary from manufacturer to manufacturer, but the principle is the same. The two types of installation are the "dry" installation method, and the "wet" installation method. A dry installation requires panels to be mounted to the flooring, subflooring, or under the subfloor. The method of radiant heat transfer, either electrical cables or tubing carrying a liquid medium, is then hooked up to the appropriate source.

In a wet installation, the heating panels are installed on the floor, and a thin layer of concrete or gypsum is spread over the installation, sandwiching the cables or tubing between two layers of either flooring or concrete. This installation is generally placed over an existing concrete slab. It is the ideal in new home construction, where a concrete slab, which has high thermal mass, is used to build the ground floor.

What to Consider Before Installing Radiant Floor Heat

Although a radiant floor heat installation can be accomplished by an experienced do it yourselfer, your best bet is to consult a heating and cooling specialist if you are considering installing a radiant floor heating system. Many things need to be considered if the installation is to be successful. These would include:

1. In an existing home installation, how efficient is the existing insulation in the home? Is there proper insulation in walls and ceilings?

2. What energy source will be used to power the installation? If you are considering electrical cable, are energy costs competitive in your geographical area? Will the electric company give you a credit for taking advantage of time-of-use rates? Check with your electric utility - the time of use rates can be a significant saving to you. Typically, the off peak times are from 9:00 PM to 6:00 AM. If you have significant floor mass, such as a concrete slab, then the radiant heat system can be "charged" during the off peak hours. An efficient installation may not require any electricity to be used during the day, when daytime temperatures are higher, and the sun helps warm the home.

3. Floor covering over the installation should be considered. Because carpeting has an insulating effect, especially when used with a pad, ceramic tile is the better choice for a radiant floor heat system. Other types of floor coverings can be used, such as linoleum or vinyl floor coverings, but remember that any covering used on the floor insulates the subfloor from the room and cuts down on the efficiency of the radiant floor heat system.

4. Although you may at the time of installation determine that the type of radiant floor heat you install is the best choice, will it be so in the future? You should also take in to consideration such energy sources as solar power, wood or LP gas as an energy source, or even a coal fired boiler if you decide on a hydronic system. Always insure that the system you install has the ability to be converted at a later date to a different energy source.

Radiant floor heat is very user friendly. It provides a comfortable heating arrangement for the home that is energy efficient, silent in operation, and friendly to the environment. People suffering from allergies, especially during the heating season, may notice a significant amount of relief, because the old forced air system is no longer blowing allergens into the home. And the best part of all is that when you get up in the morning, you don't have to put your feet on a cold floor.

Alden Smith is an award winning author and regular contributor to He writes on a variety of subjects, and excels in research.