Given the comfort and energy efficiency it provides, it’s no surprise that many homeowners today are warming up to a heating system that’s been around for a long time, radiant in-floor heating.
“It’s a creature comfort I’m enjoying,” says Nora Anzinger of the radiant in-floor heat system she and her husband chose when they remodeled a bathroom in their River Forest home almost two years ago. “Now I can walk from my carpeted [bedroom] floor to a warm ceramic tile floor in the bathroom. It’s very nice.”
Radiant floor heating comes in two forms: hydronic radiant heat, the most common form, in which heat is delivered via warm water circulated through tubing embedded under the floor, and electric radiant heat, which comes from electric mats, panels or films cemented beneath the floor and hardwired into the house’s regular electrical system.
While radiant heat has just recently come to the forefront as a heat source of choice, it’s not a new concept, according to Doug Freerksen, co-owner of Von Dreele-Freerksen Construction Co. in Oak Park. “Many turn-of-the-century homes, especially the high-end ones, had in-floor heat in their kitchens,” explains Freerksen, who has seen an increasing demand for radiant heat over the past few years. “It’s definitely becoming more popular, and there are several reasons why. It saves space, it’s very energy efficient, and it lets you dial down your ambient temperature and still be comfortable.”
“The market is averaging about 20 percent per year growth,” reports Gary Hayden, a member of the American Society of Heating, Refrigeration and Air Conditioning Engineers Technical Committee on Radiant Space Heating and Cooling and a board member of the Radiant Panel Association. “It’s still a relatively small part of the overall heating market, but it’s growing. A lot of people are looking for comfort. And energy conservation falls into it, too.”
The reason radiant heat is so comfortable and efficient is because it doesn’t heat the air around you, but like the sun directly warms people, objects and floor surfaces in a room instead. That means your body doesn’t lose heat the way it does with other kinds of heating systems. “Perfect working floor heat has a surface temperature of 85 degrees over the whole space, and the surface temperature of our skin is close to that. If your body is neutral to the space, you’re comfortable,” Hayden explains.
Since it works from the ground up, and keeps heat near the floor rather than at the ceiling, radiant heat also makes you feel comfortable at temperatures several degrees lower than those required with other kinds of heating systems, according to studies by the American Society of Heating, Refrigeration, and Air-Conditioning Engineers.
Other benefits include minimal heat loss through doors and windows, less dust than with forced air systems, and ease of zoning the heat, which allows for separate thermostats in each room.
Though no hard statistics exist on radiant heat’s efficiency, Hayden says it is widely accepted you’ll pay less for the comfort radiant heat provides. “You typically hear it’s 30 percent more efficient,” Hayden notes.
Cost, of course, depends on the weather, the area of the country in which you live, and the kind of heat you have. “If you already have a boiler, hot water is definitely cheaper [than electric]. And in the Chicago area, an electric mat would be more to operate because the cost per BTU is high,” Freerksen says. “If you don’t have a boiler, electric is the way to go, but probably only as a supplemental system because of the expense [of electricity].”
Radiant heating systems can work in new and old homes alike, though the ease and cost of installation and operation will vary, depending on things such as the size and location of the rooms you’re heating, the type of floor you’re installing, and the amount and quality of insulation, industry experts say.
According to Wirsbo Co. USA, manufacturer of hydronic radiant floor systems based in Apple Valley, Minn., tubing can be installed in standard concrete, put over suspended wood floors and covered with poured floor underlayment, placed over subfloors with tubing resting in heat transfer plates, or installed between floor joists.
In new construction, it’s simple to install because it can be put right into the concrete slab during construction. Retrofits benefit from between-the-joist installation, according to Wirsbo.
The Anzingers, for example, broke up the old tile floor in their bathroom, poured a new mud-set ceramic tile floor, and laid the tubing in the mud set, Anzinger said. She estimates that $700 of the $25,000 bath-remodeling project was for the new in-floor heat.
Electric in-floor systems can be installed on or under subfloor or in mortar or concrete.
Radiant systems can work with most any type of flooring, but are most efficient with materials that are better at holding heat, such as ceramic tile or masonry, Freerksen notes. Radiant heat can be installed in homes with wood floors, but it can be a bit trickier, and riskier, Freerksen says. “Wood is a good insulator and doesn’t hold heat for long. And [radiant in-floor heat] can dry out the wood,” he notes. “It’s not at its best under wood floors, but it’s doable. There are exceptions to every rule.”
Freerksen says his company, which specializes in older home renovations, most often installs the hot water radiant in-floor heating systems in houses with radiators. “With a radiator system it’s fairly simple,” he says, because there is already a boiler and pipe system in place, as was the case in the Anzinger’s home.
Freerksen has even installed the systems beneath garage floors and entryways, where homeowners can run antifreeze liquid instead of water through the pipes. “You put the system in before the concrete is poured. If you have salty snow all over the floor, it dries it up. And it melts snow in entranceways so there’s no need for salt and no need to shovel,” Freerksen says.
