Underfloor Heating is a Hot Market
July 1st, 2005

Remodelers and renovators are especially enthusiastic about the easy upgrade underfloor heating adds to their projects.

July-August 2005

One of the hottest renovation options to hit the home improvement marketplace is, in fact, underfloor heating. According to the Radiant Panel Association (RPA), almost 6 million nominal square feet of electric radiant panel heating elements were sold in North America in 2004!

Lawrence Drake, Executive Director of RPA, attributes the growth in underfloor warming systems to the proliferation of home improvement shows on television and to the product’s increasing availability.

Underfloor warming systems are a great addition to any tile or stone floor, but they are especially popular among remodelers and renovators—the customers who are often upgrading home amenities. The customer reasoning is clear—the opportunity to warm the inherent coolness of tile and stone, especially in cold weather, removes one of the last obstacles to installation.

As Drake points out, underfloor warming systems do not significantly heat the floor. However, he says, if you put your hand on tile, it feels cool because tile absorbs heat. Underfloor warming systems, which typically only raise the temperature a few degrees from 72 to 80 degrees, are really just neutralizing the temperature.

Not just for warming the bathroom floor

Underfloor warming systems seem especially appealing in bathrooms, where cool tile or stone under bare feet can be a rude jolt, but they are just as appealing anywhere tile floors are installed. RPA reports that they are installed in shower walls and under tub surrounds.

NuHeat’s Colin Campbell says he has discovered a niche market among custom home builders who install strips of underfloor heating along ceramic or stone countertops to take the chill off. Campbell says he also has product installed in high end resorts and boutique hotels where pampering the customer is a priority.

Depending on the amount of heat the customer wants and the type of system installed, underfloor heating can supplement or substitute for traditional heating sources. They are ideal for situations in which the homeowner or remodeler does not want—or finds it too expensive—to extend expensive heating systems to new spaces like room additions, sunrooms, finished basements and garage conversions.

Radiant heat has long been prized by the energy efficient.

How underfloor heat works

Most underfloor systems use an electric resistance cable that snakes along the substrate. The cable may or may not be encased in a mat. Both the cable and mat systems adapt to curves and angles in the floor layout. Virtually all municipalities require a qualified electrician to connect the cables and thermostat to a dedicated circuit in the building’s electrical system. The cable and mat—if that is the type of product used—are encased in thinset or leveling cement before proceeding with the tile or stone installation.

An alternative system uses hydronic heating, snaking flexible water tubing on the substrate which will eventually be filled with hot water to provide radiant heat. This too is a growing product category, but one that is more conducive to new construction since it requires the installation of plumbing and boilers.

Ben Abraham, general manager of DK Heating Systems, says his company was the first to use cable in a mat or panel in the early l’80s. His product comes in a 1- by 20-foot continuously rolled mat that is easily cut and turned to custom fit any floor layout.

NuHeat’s Colin Campbell says the company’s mat system comes in sixty different sizes that may be used in various configurations to suit a room layout or the company will produce a custom mat to fit specific curves or angles.

Campbell points out that installation is very easy. It begins with a dry fit layout, then the installer removes the mats, applies thinset and lays the mats back down, “stomping” them into the thinset. More thinset is applied after this. Because the product is only 1/8-inch thick, this does not significantly raise the floor level. And, he says, it’s an “affordable luxury,” since it only costs $500-$1,000 for the average bathroom installation.

Delta Therm Corporation produces a free-form cable and strapping system that anchors to opposite ends of the installation. Marketing Manager Ada Cryer says the cable is woven back and forth like a loom, making it especially easy to conform to the size and angles of a specific space. The cable can be tabbed closer or farther apart depending on the desired heat output. The cable is then embedded in a ¼-inch layer of skim coat.

The company, which entered the floor warming marketplace seven years ago, has been in business since 1968 and produced the first UL listed snow melting cables in the early l’70s. Delta Therm offers the Floor Warner monitor, which sounds an alarm if the cable is damaged.

Step Warmfloor offers yet another floor warming system.

The product is an innovative polymer blend mat that heats when electricity is passed through the mat. Advantages include the low-voltage necessary to use the material; it typically uses a 24-volt transformer but can be operated by a solar- or wind-powered source.

Step Warmfloor senses warm spots from the sun, a piece of furniture or even a rug. The black carbon in the mat expands with warmth or contracts with cold. Company president Monica Ingress says this self-regulating feature really turns the whole floor into a sensor. The system automatically compensates for hot or cold spots.

WarmUp uses yet another variation on the basic principles behind floor warming. Sharon Mangino, general manager of U.S. Operations, explains that the product is essentially an easily-installed wire specially coated for water resistance. The wire, which is UL listed, is only 2 ml thick. It comes in a kit with a primer to prepare the substrate and special tape to anchor the wire. Mangino says the use of an insulated backer board helps prevent heat loss below the floor. Once the wire is installed, it’s easily buried in thinset and the floor is ready for tile.

Installation is easy and because the mat is so thin—just 3/64-inch—it does not impact the height of doors, moldings or cabinets. Although it can be used for whole-house heating, even in very cold climates, it’s most often installed to heat specific areas such as under tile or stone.

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