If you have ever walked barefoot across a New England tile floor in winter, then you know it’s true when they say that heat rises.
But what if the heat actually started at your toes, instead of blowing in from a vent near the ceiling or a radiator in the corner of the room? Radiant heating systems, in which the warmth actually runs uniformly underneath the floor, do just that.
What is Radiant Heat?
Using either electricity or warm water, these networks circulate heat underneath the floor. Want to keep your bedroom toasty but not the guest room that’s rarely used? Radiant heat systems can use multiple zones based on your preferences. This flexibility, which can lead to lower utility bills as well as a reduced carbon footprint, is growing in popularity. Between 2000 and 2006, sales of hydronic, water-based heating systems have more than doubled in the U.S., according to the Radiant Panel Association.
“People like the idea of comfort,” says Lars Andersen, owner of AIM Radiant Heating in Acra, N.Y., which creates customized radiant heat systems for contractors and do-it-yourselfers. “Also, it is not something that you have to work around as far as your furniture placement or where you are putting in cabinets.”
Radiant heat systems can also save time—as well as your back. Outdoor systems installed underneath driveways and walkways use sensors that monitor temperature and moisture. When it snows, they switch on, which means you can sell your snowblower at your next yard sale. The same technology can help prevent snow and ice from collecting on your roof and in your gutters.
“Our most popular product right now are the snow melting systems,” says Tracy Stanger, president of Warmzone in Salt Lake City, Utah, a radiant heat system supplier. “Most of our business is done for exterior snow removal, snow melting in the driveway, the sidewalk and loading docks.”
Types of Systems
Radiant heat systems come in two varieties: hydronic and electric. Which system to choose depends on your heating needs. If you are building a new home and want a totally radiant heating system, hydronic is the most cost-efficient. If you’re renovating your home and want to add supplemental heat, such as to a bathroom or kitchen floor, then electric is best.
“The cost of electric floor heating per square foot is significantly higher than the hydronic system,” says Nicolas Mottet, marketing communications manager with Warmly Yours of Chicago, an electric radiant heat company. “As a result, you are going to find electric floor heating in small spaces. The bathroom is the number-one selling room and then the kitchen or maybe a basement. It is basically to add controlled extra warmth to just a couple of rooms in your home.”
Depending on the size and complexity of the job, both hydronic and electric systems can be do-it-yourself jobs. AIM Radiant Heating specializes in a “Boiler Room in a Box,” which are customized units that come with simple step-by-step directions for installing the tubing and the pre-assembled central heating element. Money can be saved because the homeowner can do most of the labor. However, a licensed electrician or plumber is needed to do the final system hook-ups.
Installations come in two varieties: wet and dry. In wet installations, the cables are embedded into a concrete slab or thin layer of concrete or gypsum on top of a subfloor. This is a common installation method for electric systems under tile floors.
In a dry installation, there are two options. In the first, hydronic cables or tubing run in an air space beneath the floor. This is commonly done in spaces where you have access to the joists. A second dry method that is growing in popularity uses subfloor plates or boards equipped with Pex tubing and aluminum diffuser plates. The water heat is spread uniformly, and flooring such as hardwood can be nailed directly to the subfloor. Unlike poured concrete, this method does not add significant height or weight to the floor.
Radiant heat is more efficient than baseboard or forced air heating because no energy is lost in the ducts, says the U.S. Department of Energy. Also, hydronic uses little energy and can be heated through a variety of sources, such as gas, oil or wood-fired boilers or solar water heaters. Electric systems used in small spaces are low-cost luxury, adding only 5 to 15 cents per day to your electric bill.
Radiant heat systems are also space-savers. “We currently have two remodels right now and in the bathroom area the quarters are so tight that they really do not have room for a traditional radiator,” says Jay Irwin, president of Irwin Design and Build Inc. in Potomac, Md. “These are older homes that have hot-water powered heat, so they have radiators throughout the house.”
Factors to Consider
Heating costs, especially with electric systems, can be considerable. They are most efficient when installed in or on a concrete floor, and if your electric provider offers time-of-use rates that allow you to charge the floor with heat during off-peak hours, such as 9 p.m. to 6 a.m.
Also, radiant heat requires some patience. You can’t walk in from the cold, turn up the heat and expect to feel toasty within minutes as you would with forced air. Hydronic systems in concrete slabs have a slow thermal response time, which means it is best to keep a constant temperature in your home instead of lowering it at night and raising it during the day.
Flooring options are also limited with radiant heat. Vinyl, linoleum, carpeting and wood flooring can be used but they decrease the system’s efficiency, says the Department of Energy. “Carpet is a tough call,” says Stanger. “I have kids; I would not want them poking something down in the carpet. Also, it’s an insulator so it does not allow heat to transfer through it as well as like tile or hardwood.”
Wood flooring can be used, but it must be laminate because heat can cause solid woods to shrink and crack. “Hardwood gets a little bit difficult because a lot of times it can void the manufacturer’s warranty if it is not the right type of hardwood flooring,” says Irwin.
Another thing to consider is the cost of repair. Experts say that once these systems are installed properly, the failure rate is close to zero. If there is a problem, human error is usually to blame, such as the homeowner who has hardwood flooring installed without telling the contractor that there’s radiant heat in the floor.
Some people avoid radiant heating systems due to health concerns regarding electromagnetic fields (EMF) in electric radiant systems. Some studies have pointed to a possible increased risk of cancer. But Warmly Yours informs customers that EMF levels from electric radiant heat are 50 to 500 times lower than the acceptable level and much lower than those emitted by most household appliances such as microwaves.
If you need help determining which system is best for you, and how to design it to best meet your needs, contact a radiant heat supply company for a free consultation. Using your floor plan, the company will do a heat loss calculation and determine a layout and the amount of assembly components you’ll need for the project.
Preplanning is especially important if you want to add radiant heat either to your newly constructed home or during a remodel. That’s because radiant heat is very easy to install before your floors go in but much more of a challenge once the cement has dried.
Credit: Renovate Your World