Construction Products Review: Radiant Floor Heating SystemsHomeowners rave about toasty tiles and warm wood floors.

  • By Jeffrey Lee
  • Source: BUILDING PRODUCTS Magazine
  • Publication date: 2006-11-23

Radiant floor heating just might be the oldest luxury heating technique in history. Roman engineers, faced with the task of heating enormous bath houses, developed a heating system called the hypocaust: a floor raised on pillars over a hot furnace, creating warm floors and a toasty room.

In modern times the technology has changed, with polyester mesh electric heating mats or flexible plastic tubing replacing wood-burning furnaces. But the effect is the same: luxurious, warm floors that heat the room and pamper the body.

Today the technology is growing faster than ever, fueled by advances in materials, concerns over heating prices, and homeowners'desire for spa-like bathrooms that indulge their desire for comfortable surfaces. Owners of heated floors notice the comforting heat at first, but, as with the sun, the floors become second-nature necessities over time, says Dan Chiles, vice president of marketing for Watts Radiant.

"Homeowners are emotional about their radiant floor," he says. "They'd rather give up their roofs than their radiant floor."

Watts Radiant offers two floor heating options for builders and remodelers, with different applications. Electric mats usually are used just for floor warming, rather than as a primary heating source. Because they are quick and easy to install, they often are used in remodeling. Hydronic or hot water heating, on the other hand, is often installed throughout a house and can serve as the primary heat source. Installing the pipes and related infrastructure requires more planning and time, however.

"If [homeowners] want hot water, they have to decide very early on," says Steven Klenk, vice president of home builder Pinnacle Custom of Millburn, N.J. "The construction of the home almost revolves around whether they want radiant or not." Klenk says his firm installs both hot water and electric, adding that if the home already has a boiler servicing a baseplate, it makes economic sense to employ hot water heating.

More Floors

A Radiant Panel Association (RPA) survey of manufacturers and primary importers found 2005 sales of hydronic tubing at 333 million feet, an increase of about 36 percent since 2003, though virtually flat since 2004. The survey also estimated North American electric radiant panel element sales at 6.2 million nominal square feet in 2005, a 7 percent rate of growth after sales numbers almost tripled in 2004. While growth appeared to stagnate last year, Larry Drake, executive director of the RPA, says it may just be the result of industry consolidation. "Everybody seems to agree that the industry is booming," he says.

Much of the growth seems to come from a realization among consumers that radiant floor heating is not as expensive as it once was. Manufacturers estimate the average cost of a bathroom electric radiant heating system, including programmable thermostat, at less than $1,000. "Ten years ago people thought of electric radiant heating as something to do if you won the lottery," says Kevin McElroy, vice president of sales for Nuheat. "Now it's the next necessity."

Because material prices are low, more homeowners are installing floor heating all around the home. While McElroy says 80 percent of his company's products are used in kitchens or baths, contractors and installers are putting radiant floors everywhere from foyers and galleries to basements, breezeways, garage conversions, and room additions. Some homeowners are installing radiant heating under shower floors and chilly granite countertops. "So they're putting electric mats on a plywood base then under the granite countertop," McElroy says. "You're really getting luxury stuff here."

Radiant floor heating also is showing up in moderately priced housing. "We're seeing it in high-end residential construction down to the average home," McElroy says.

Meanwhile, Drake says that a burgeoning emphasis on green building should drive the growth of radiant heating. "Radiant is undoubtedly the most healthy heat system out there," he says.

With the costs of electricity, gas, and oil rising, homeowners find the potential energy savings of radiant heat appealing. McElroy says that Nuheat's electric floor mats, for example, draw only about 12 watts per square foot. "It's a fallacy that it'll cost a lot to run," he says. "The whole system uses the same amount of electricity as the light bulbs in a room." Additionally, most electric floor heating systems come with programmable thermostats, allowing the
homeowner to turn on the heat for just a few hours a day.

Hydronic is hot

While hot water radiant floor heating does not have the advantage of programmability, new technologies are producing energy savings. In the past, most hot water systems were built using the staple-up method—n which hydronic tubes are stapled to the underside of the subfloor—or the wet pour method, in which the tubing is embedded in poured concrete. But staple-up is less efficient and requires higher water temperatures, and the wet pour method requires days or weeks of installation time as well as additional framing reinforcement.

New "dry" modular panel systems, made of aluminum or concrete in a plastic shell, for example, allow installers to quickly construct a hot water heating system that conducts heat as well as or better than a concrete slab. "The trend is to go with more dry systems," says Lance MacNevin, manager of heating and plumbing technical services for Rehau.

The more efficient panels also allow homeowners to take advantage of high-tech condensing boilers. "The condensers are more efficient at low temperatures, so you can crank out 99 percent efficiency on a propane or gas boiler," says Jim Bolduc, owner of Jim Bolduc Plumbing and Heating in Cumberland, Maine.

Furthermore, radiant systems also can be constructed to take advantage of solar or geothermal systems. "When gas and oil goes to $5 per gallon, we're going to be putting in better equipment and customers are going to want to pay for it," Buldoc says.

A growing awareness about radiant floor heating due to publicity from home magazines and TV shows like This Old House, means that builders and remodelers have an opportunity to upsell their clients. "At first they think it'll be way too much money," says Dave Tazzoli, owner of Marble and Tile Design in Lake Bluff, Ill. "Then they see it'll be pretty reasonable."

While the initial cost and hassle of the installation is higher, the payoff in both comfort and energy savings for the homeowner and profit for the contractor is worthwhile, installers say. "It's labor-intensive, but it's the most rewarding system to put in because you can get the most satisfaction from the homeowner and you can make a lot of money from it," Bolduc says.

–BUILDING PRODUCTS

Rehau

Rehau. The Raupanel radiant heating system consists of 3/8-inch Raupex cross-linked polyethylene pipe, aluminum panels, and wood return bends. The heat transfer efficiency of the aluminum panels allows for reduced water temperature, and the panels'relatively low thermal mass gives them quicker response time, according to the manufacturer. The system's 5/8-inch profile has minimal impact on floor height, the firm adds. 800-247-9445. www.rehau.com.

Nuheat

Nuheat. Constructed of thin heating wires embedded in a 1/8-inch-thick mat, this electrical radiant floor warming system is available in 110V and 220V formats and more than 60 standard mat sizes, as well as custom sizes for curves and angles. The MatComfort thermostat has pre-programmed settings and programmable seven-day settings. 800-778-9276. www.nuheat.com.

Warmly Yours

WarmlyYours. The firm's electric floor warming kits, sold direct to the remodeling community, include a floor warming system, manufactured in roll form for fitting around fixtures and cabinets, as well as an installation guide, DVD, a system check electronic aid, and warranty registration materials. Homeowners and professionals can request custom designed floor warming systems for uniquely shaped rooms. 800-875-5285. www.warmlyyours.com.

CPI

CPI. Basic Radiant modular installation kits include a pre-assembled and pre-tested control panel, Dura-Pex or Barrier-Pex, fittings, tools, valves, manifold, and crimp rings. The firm offers five different control panels, which cover anywhere from one to four different zones and up to 5,000 square feet of floor. The company also offers an installation DVD. 800-489-8274. www.durapex.com.

Electro Plastics

Electro Plastics. The Step Warmfloor electroplastic heating element is different from hydronic and cable heating systems because it is made of a thin, homogeneous, semi-conductive polymer that is self-regulating, meaning it draws only the energy required to maintain the ideal temperature, the manufacturer says. The technology also eliminates thermal mass and expansion issues, according to the company. 877-783-7832. www.warmfloor.com.

Easy Heat

Easy Heat. The Warm Tiles electric floor warming system is designed for tile, stone, and engineered wood floors. Cables can be installed in any design configuration, while pre-fabricated mats on a mesh backing are suited for concrete slab or multi-unit applications, as well as for square and rectangular rooms. Thermostats include a floor sensor embedded in the mortar below the tile. 800-537-4732. www.warmtiles.com.

Warmup

Warmup. The Undertile Heating Mat system's dual-core heating element requires the wiring of only a single power lead. The heating element is made of two layers of insulation and metallic braided grounding wire wrapped around a dual-core heating wire. Pre-sized mats are available in a variety of sizes for rooms 16 square feet or larger. 888-927-6333. www.warmup.com.

Infloor

Infloor. The firm makes hot water and electric radiant floor heating systems. Among them are the InfloorBoard modular hydronic system, made of composite boards with an aluminum layer for quick heating acceleration, according to the manufacturer. Alternatively, Radiant Trak plates are installed facing each other between the joist spaces on the underside of the sub-floor, keeping the heating pipe in place. 800-588-4470. www.infloor.com.

Delta-Therm

Delta-Therm. Made of flexible stranded resistance wires and covered by an inner thermoplastic elastomer insulation, a durable copper braid, and a TPE overjacket, the DeltaWarm DW Floor Warming Cable is only 1/10-inch thick, so it will not significantly raise floor height, the manufacturer says. The company also offers ClipStrip attachment strips and includes installation instructions for the cable and thermostat. 800-526-7887. www.delta-therm.com.

Watts Radiant

Watts Radiant. Watts Radiant manufactures a variety of electric and hydronic radiant floor heating products, including PEX pipe, temperature gauges, controls, valves, electric floor warming mats, and manifolds. SunTouch radiant heat mats are designed to warm stone and tile floors and have a special braided twin wire design that registers no electromagnetic field 1/2 inch above the wire. 800-276-2419. www.wattsradiant.com.

Viega

Viega. ProRadiant heating systems are designed to be used with any type of floor covering. The Climate Panel radiant underlayment system, engineered for wood frame construction, is made of aluminum-backed plywood with grooves designed for Viega PEX tubing. The Snap Panel grid system is used for regular or lightweight concrete applications. 877-843-4262. www.viega-na.com.

Bylin Engineered Systems

Bylin Engineered Systems. Attached directly to the subfloor and embedded in the mortar or thin-set under the flooring, WarmGlo radiant floor heating cables are designed for tile, marble, slate, and other stone surfaces. The cables are made of an alloy heater element wrapped with 4-mil Kapton, and then encased in silicone rubber, a ground braid, and another layer of silicone rubber. 916-933-5666. www.bylinusa.com.

Ipex

Ipex. WarmRite Floor radiant heating system components include Kitec XPA pipe or PEX tubing, pre-assembled control panels, supply and return manifolds, and accessories. The system can be installed in slab and basement floors, staple-up applications, or topping pour for tile floors. The K-Tile radiant floor underlayment secures XPA pipe without carpentry, fittings, or adhesives. 800-463-9572. www.ipexinc.com.

Thermosoft

Thermosoft. ThermoTile radiant flooring, pictured, is best suited for tile, marble, stone, or porcelain floors, according to the manufacturer, but can be installed under any floor surface when embedded in thin-set mortar. The product is constructed of fiberglass mesh with a 1/8-inch-thick heating cable. QuietWarmth flooring is designed for laminate, wood, and engineered wood floors and replaces generic underlayment pads. 847-279-3800. www.thermosoft.com.

Honeywell

Honeywell. The company's prepackaged floor warming kits, sold to new home builders, are designed for bathrooms with open areas up to 40 square feet. The company also provides a free design service with overnight system design drawings and pricing for larger bathrooms, kitchens, and other rooms. The kits include a complementary line of floor warming system thermostats. 866-891-9276. www.honeywellfloorheating.com.