Underfloor radiant heating was first used by the Romans and while the technology was effective, it required labor-intensive installation and was limited to public buildings. Today, the basic concept of underfloor heating is the same, but technology is considerably more advanced, installation is simplified, and the product is available to the masses.
With radiant heating, radiant energy is emitted from a heat source and then penetrates all objects in its path, including people. The heat energy is emitted from a warm element — overhead panel or floor — and warms people and objects in the room rather than directly heating the air. Radiant overhead panels are most commonly used in commerical applications such as production and warehouse facilities, while underfloor heating systems are most popular in residential settings.
There are two options in underfloor heating systems, hydronic and electric, and while both are efficient, considering the area of application is usually the best way to determine the appropriate product. In a hydronic system, heated water travels through tubing embedded in the floor. The floor absorbs the heat and emits radiant heat which warms objects and people in the room. An electric system works the same way but uses electric heating elements to warm the floor.
“The remodeling contractor has to understand the owner’s priority,” says Dan Chiles, vice president of marketing for Watts Radiant. “If the house is to be turned quickly or if it is built as a spec project, the builder can’t afford to spend a lot of money on radiant. So, a small electric system in the master bath is perfect. A whole-house radiant system is best when the owner wants the most efficient and comfortable house. Comfort and efficiency are the two great selling features of radiant, and those are probably not the highest priority items for a spec home builder.”
“Initial cost and ongoing maintenance play an important role in the decision process,” says Sharon Mangino, Warmup, Inc. general manager of U.S. Operations. “Electric radiant heat is widely considered for remodeling; however, we are starting to see an increase in interest for new construction, especially for customers who do not want the expense of installing hydronic systems.”
“Electric is commonly used in ‘spot’ heating for what I would consider a bathroom or small kitchen,” explains Jeff Wiedemann, Uponor associate product manager, heating. “Economically, it can’t be justified to add a heating device [boiler, water heater, etc.] and the expense associated for 100 sq. ft. It is much easier to tap off existing electrical circuits for mat heating.”
Radiant heating is a brilliant way for builders and remodelers to differentiate themselves from their competition. These products provide pampering for the end user, and manufacturers have made them quite simple for the installer.
“One of the main benefits builders can expect to see by offering radiant heating is the elevated level of differentiation between you and your competitors,” says Dave Zweber, builder marketing manager for Uponor. “In the highly competitive custom home building arena, builders are always looking for a way to set themselves apart from the crowd. Builders that feature radiant floor heating systems are seen as innovative and forward thinking by the distinguished and highly sophisticated target market for custom homes.”
Uponor Wirsbo recently introduced the proMIX 701 Injection Mixing Station. The unit is a weather-responsive, single-temperature reset station with integral variable-speed injection and secondary system circulators. The most common application for the proMIX 701 is one requiring only one supply water temperature such as the lower level of a home or a single-story, slab-on-grade home.
Dan Chiles adds, “Radiant also gives interior designers more options because there are no ducts or radiators. People love the quiet of warm floors and the fact there aren’t drafts blowing all over the house. Home improvement shows have discovered radiant heating, so there has been a lot of public attention on the subject.”
To keep projects on schedule and on budget, Watts offers HydroSkid units that are built entirely to specification.
HydroSkids are ideal for larger, more complex hydronic applications, and are available in an infinite number of configurations. They are assembled with the customer’s specified controls, pumps and requirements. Units are fully constructed at the factory and delivered ready for fast hookup. When complete, the unit is attached to a durable mounting surface for shipment and jobsite placement. Skid sizes vary according to system requirements.
The Danfoss LX Electric Floor Heating promises safety, reliability and energy efficiency. To facilitate easy installation, the Danfoss systems are complete with preapplied heating cable, single point connection and self-adhesive backing for quick installation, and they are backed by a 10-year warranty. The system also includes an electric thermostat that controls temperature by an external or built-in sensor. The heat output is switched on or off with a difference of 0.7 degrees F (0.4 degrees C).
Warmboard is the only radiant heat panel and structural subfloor in one. APA-rated high-strength tongue and groove plywood combined with a thick aluminum layer creates a state-of the-art low-mass, high-performance radiant heat panel.
Warmboard is compatible with all floor coverings. Ample heat is delivered through even the plushest carpeting. Tile and stone can be set over it, and hardwood nailed directly to it. Warmboard panels install easily as part of standard wood framed construction. Easy-to-follow panel and tubing layouts are supplied for every project, ensuring a simple and smooth process. Additionally, the high conductivity of the panel leads to lower water temperatures, which ultimately benefits the environment.
Cost is a prime consideration in the type of unit installed, but it is not the only aspect. Plumbing, wiring and insulation are also important concerns—not deal breakers, but definitely something to think about.
“Electrical specifications, additional wiring, subfloor types, insulation and the type of flooring need to be reviewed when considering electric radiant heat,” says Sharon Mangino. “These are not problems, but factors that require consideration. We make product recommendations based on the type of floor being installed.”
“Radiant floors are typically used for heating, so most people install a dedicated cooling system to go along with their warm floor,” advises Dan Chiles. “That means the whole HVAC system will cost more money. First cost is always the biggest issue with radiant. Be sure to insulate your floor well. Maybe you feel you can get away with less floor insulation in a typical forced air system, but don’t try that with a radiant floor.”
Uponor Wirsbo, Inc. recently introduced the D’mand Hot Water Delivery System to provide hot water quickly for energy and water savings. It is installed with the Wirsbo Aquapex plumbing system. D’mand features a pump, which is activated by either a button or a motion sensor located near the plumbing fixture — the kitchen sink, bathroom sink or shower. Once the pump is activated, hot water reaches the fixture in just seconds. The D’mand system uses a structured plumbing layout incorporating a loop of tubing that starts at the hot water supply line and returns to the heater where it tees into the main line supplying cold water to the heater.
Calorique’s ThermoWeave features double-insulated, all-metal heating ribbons that gently warm floors to distribute heat evenly throughout the living space. For easy installation, just lay down insulation and roll out ThermoWeave mats on an existing floor; then finish the surface normally. ThermoWeave is approved for installation under any type of floating floor, including laminates such as Pergo. ThermoWeave can also be embedded within concrete or tiling adhesive for use in bathrooms and kitchens.
Warmzone’s electric heating cable systems are available for small areas such as the bathroom. Electric cable systems are efficient, easy to install and cost-effective. The system is controlled by a thermostat with an in-floor sensor, and promises to be maintenance-free. To complement the warm floor, the company’s Web site, warmzone.com, offers towel warmers from Zehnder.
For even more simplicity and spot warmth, WarmlyYours offers the ComfortPlus floor warming systems that fit discreetly beneath area rugs throughout the home. Employing the very latest in highly durable, micro-thin warming technology, ComfortPlus systems measure less than 1/4 in. thick (including integrated nonslip pad) allowing them to be hidden beneath area rugs. Homeowners need only position the warming pad beneath their area rug and plug the power cord into any standard 120-volt outlet.
The radiant heating market is rapidly picking up steam. Ever-rising fuel cost is a major driver in the popularity of radiant heat but so is consumer demand for in-home luxury.
Jeff Wiedemann attributes this increase to “consumers having a better awareness of products and technologies that provide them better environments to live in: comfort, efficiency and indoor air quality.
“Currently the largest market for radiant heating is in the Northeast; however, the trend is sweeping quickly across the country including much of the Midwest and the Rocky Mountain region and the Northwest,” says Wiedemann. “Areas in the South have been slower to adopt the technology; however, there is definitely an increasing demand. We see UFH installed throughout any cold weather regions throughout North America. We also see radiant heating systems installed in the South as well. Think of Florida. Traditionally not a heating market but we see installations to warm the marble and stone.”
Dan Chiles says, “Radiant has shown spectacular growth over the past 15 years and we have gotten our share of that. Of course, we’ve had a great housing market until recently, and now we think the public and specifiers will be more focused on overall energy efficiency.”
The Watts SubRay is the newest way to sandwich radiant tubing in a low-profile subfloor and is priced competitively. With SubRay, an installer secures ASTM standard 3/8- or 1/2-in. radiant tubing at two opposite sides of a room with cabinet grade, 11- or 17-ply Baltic birch “header sticks.” Between these are “sleepers” that organize the tubing into 2-in.-wide radiant channels that are spaced on 8-in. centers. Beneath the tubing is aluminized Mylar tape that reflects energy upward to an aluminum diffusion layer that extracts heat closest to the floor surface, spreading warmth to the entire finished floor.
According to Sharon Mangino, “electric radiant heat has been popular for many years in Europe and it is an idea whose time has come in the United States, regardless of region and weather conditions. Warmup, PLC, a London based manufacturing and sales organization, dominates the market in the UK. They realized the potential in the United States and opened an office in Connecticut four years ago. Warmup is averaging more than 50 percent increase in sales per year and expects this trend to continue.”
“What surprises us is the recent rapid growth and awareness of radiant heat in the United States,” says Mangino. “A couple of years ago, customers wanted to know what our product did. Today, our customers are savvier about the benefits of offering radiant heat products. We have more opportunity to define the simplicity of our product applications and help our builders to promote an innovative and efficient product to their customer, while adding a new revenue stream to their business.”
Warmup is introducing a 240-volt loose wire to their existing product line this month. The products give builders the option of installing loose or mat heaters in 110/120 or 220/240 volts. The loose and mat heaters are also compatible with each other so the heating system is flexible enough to accommodate any size or shape room.
Service and Support
In the relatively new radiant heating market, questions and concerns are bound to arise, but manufacturers offer plenty of information and support to ensure their products are sold, specified and installed correctly.
“People think electric radiant heat is expensive,” explains Mangino. “The ability to zone every room and program the thermostat for efficiency can save homeowners up to 15 percent on their heating bills. It’s good for the environment; it’s clean, quiet and requires no maintenance.”
Warmup products feature a UL listing to ensure safety and are supported by a Safety Net Guarantee on their first job. If they accidentally cut or damage a heater, prior to installing their floor, Warmup will replace the heater free of charge. Warmup also offers a 24/7 technical support line, and technicians and sales force members are available to assist in specifying the job in advance.
The Viega crosslinked PEX tubing is extremely durable and will not break in use. If the PEX tubing is accidentally punctured during installation, a repair coupling would be used to eliminate the damage. Viega offers a 25-year warranty on ViegaPEX Barrier tubing used in hydronic radiant heating applications. Viega PEX tubing is expected to have a life that will outlast the structure it is installed in.
“Uponor operates very much on a relationship basis with the builder and architectural community,” says Dave Zweber. “We made sure their every need is met and that they have the resources and training they need to confidently represent our product. We understand that in order for our company to be successful, the builder and architects need to be comfortable and confident in our products and that they are able to profit from featuring our systems.”
Dan Chiles notes, “I’m surprised that radiant is not used in every house project. I’ve never seen a home product with higher personal satisfaction. Customers tell us they would rather give up their roof than their radiant floor.”