Radiant heat floors:<br>Affordable, efficient comfort for cold feet

Although radiant heat can be installed using a number of methods, the under floor installation seen here is well suited to buildings under construction. The radiant tubing is simply stapled onto the joist bay.

Without question, warm floors are the most comfortable form of heat you can have in a home. And the more consumers come to realize this, the more likely they are to inquire about the advantages of radiant heat. This is a development that has thrust flooring and design professionals into the radiant realm.

There are many ways to deliver radiant heat to existing and new floors. There are even systems that offer snow-melting options for safe access to a home or commercial facility. Here, then, is a brief introduction to the technology.

Simply put: Radiant floor heating uses water-filled tubes or electric heating elements to warm an entire room. The surface of a floor (or wall) gently emits heat energy that moves gracefully to all the objects in the room, making them - and your feet - feel warm and cozy.

The radiant heat from the floor will warm all of the solid mass in the rooms and give every surface an inviting sensation. Surprisingly, those surfaces most uncomfortable without radiant heat - stone, tile and hardwood floors - can become the most comfortable with radiant because they transfer the heat so well.

Apart from the comfort level created by this type of heating system, there are these important benefits to consider:

Efficiency. There is wide agreement that Radiant heat offers the highest energy efficiency available. These systems are typically 25 percent to 30 percent superior to forced air systems in terms of energy consumption.

Room Design. With no air grates, radiators or baseboard to factor-in there's no interference with room function or furniture layout.

Energy. Radiant heat systems can be powered by a variety of energy sources or and sometimes even a combination of two or more. Fuel oil, gas, electric, solar, ground source heat, and other solid fuels can be employed.

Health. Allergy sufferers usually love radiant heat. In many instances, allergy problems are eliminated in homes with radiant heat. Also people who suffer from arthritis or poor circulation will appreciate the warmth of radiant.

Of these the cost factor is frequently overlooked. Many consumers don't understand that radiant floor heat costs less to operate than other forms of heat. That's primarily because radiant floors offer more comfort at lower thermostat settings. Heat from a radiant system also doesn't stratify at the ceiling. Another advantage is the "zonability" of radiant heat - the ability to have thermostatically controlled zones throughout the home is the essence of control.

Hydronic (water based) radiant floor systems are mostly used in a large area, such as an entire home or commercial facility. Generally, hot water radiant is best for spaces 500 square feet or larger, or in a building where hot water is already used as a heat source. Hydronic tubing can be embedded in concrete slabs, in thin-slabs over frame floors, stapled up between floor joists, or installed on the subfloor.

An electric system may be the best choice for small areas like a bathroom. Of course, if it economical to do so electric energy can be used to heat, or provide floor warming, to an entire home. Typically, low-profile electric floor radiant systems are installed directly into the thinset used to set a finished tile or stone floor. Warm solid surface floors are popular for master bathrooms, entries, kitchens and sunrooms.

SunTouch, for example, offers mats with a woven-in heating element. They are available in rolls that are 12-, 24-, 30- or 36-inches wide with lengths up to 80 feet. These can be shaped on the jobsite to fit any floor plan. Another type of electric system is HeatWeave which involves attaching spacers to the subfloor, and stretching a wire back and forth between them that's attached to the spacers (EasyHeat). Yet another uses low voltage screens that can be stapled directly to the subfloor.

Workers seen here installing SubRay by Watts Radiant use aluminum heat emission plates to maximize the system’s efficiency. The engineered above-subfloor product was selected because it is designed to produce excellent BTU output. It is likely to prove useful in this remote mountain top house in Pennsylvania, which has high ceilings and many windows.

In most instances, installers working with electric radiant products first attach a cementious backer board over the subfloor. The mats are then stapled or taped to the backerboard and thinset mortar is applied with a notched trowel just prior to setting tile or stone.

Another option, especially well suited for remodeling projects where the existing solid surface floor has no heat, is a new type of electric radiant mat that is UL approved for joist bay applications. If you have access to the framed underside of the floor, these mats can be secured within the joist bays, just under the subfloor, and then insulated.

When a new home or addition is under construction, radiant heat can be included anywhere including floors, walls or ceilings. One technique is to staple radiant tubing to the top of the plywood subfloor. It's then covered with a thin slab of lightweight concrete or gypsum based masonry. Joist bay staple-up is also popular for new construction and retrofits.

In those instances when you can gain access to the floor from below, simply staple the radiant tubing directly to the underside of the subfloor. To enhance efficiency and heat transfer, aluminum heat emission plates can be used; these sheet metal pieces attach to the pipe and are then stapled to the subfloor. Typically, a foil-faced batting insulation is then attached two-or three-inches below the pipe. This method is appropriate for any type of floor covering and does not affect the finished floor height.

There are a variety of other products suitable for new construction or remodeling. One method offered by a few manufacturers provides excellent BTU output per square foot. For example, SubRay plywood sleepers are screwed to the subfloor and tubing is laid between them. A floor installer then bridges over the system with any finished floor using hardwood, a laminate product, tile or stone. This method increases the finished floor height by a 1/2- to 3/4-inch.

The key to a successful first venture into radiant heat is to enlist a professional installer with radiant heat experience. Your customer's toes deserve the happiness only radiant heat delivers.

For more information on Radiant Heat

Electro Plastics

(314) 781-2121, www.warmfloor.com

Flextherm

(450) 442-1099, www.flextherm.com

The FlorHeat Co.

(888) 265-5455, www.florheat.com

Infloor Radiant Heating

(763) 478-9660, www.infloor.com

MP Global Products

(888) 379-9695,

www.mpglobalproducts.com