Electric heat often is more expensive than heat produced using combustion appliances, such as natural gas, propane and oil furnaces, due to electricity generation and transmission losses. But it has distinct advantages in certain situations, which may include cost benefits in both commercial and residential applications.
“Electric heat is very easy to install. An electric heater can
work as a stand-alone unit or as a system. It doesn’t require any pipe work—simply a connection to electrical circuits. For new building properties, it can get installed in the wiring stage. For remodels, there is minimum disruption for households, such as digging for the gas lines,” said Wally Cisewski, vice president and owner, Medina Electric, St. Paul, Minn.
Electric heat is basically an electrical appliance that converts electrical energy into heat. Different types of electric heaters deliver the heat in different ways. For offices, electric heat is used in specific and convenient applications.
“Usually, every commercial building has a package rooftop unit that is a combination heating/air conditioning unit. And depending on how many of those units you put in a building, you may have to have supplemental electric duct heaters through the system. Electric duct heaters are used to zone off certain office areas because they get colder or warmer based on the number of windows and amount of use. Electric heat is, in most instances, a supplemental heat,” said Frank Vaughan, president, Superior Electrical Systems Inc., Naperville, Ill. “Anywhere it doesn’t make sense to run a duct would be where you’d probably use electric heat. It’s installed to help a larger heating unit, to help keep it regulated.” Stairwells or garages would be areas where a duct would not make sense.
“There are areas in a parking garage, stand-alone situations—mechanical spaces, electric rooms within parking structures or the parking manager’s office—where it might be easier to heat with electric heat because the area doesn’t require any other equipment. That would be versus a heat-pump system that would have air handlers, heat pumps and other things, which are more efficient in an office environment,” said Paul McCluskey, president, Edward G. Sawyer Co. Inc., Weymouth, Mass.
Electric heat also is used for snow and ice melting. Heat tracing—the application of electric heat to piping, tanks, instrumentation and other equipment—is used against the cold. Tape products with electrical wires within are applied to prevent ice or snow buildup and are wrapped around water piping, run through gutters or around down spouts.
“It can help by zones,” Vaughan said. “For roofs, we lace tape in a V formation and zigzag it up and down around the perimeter of the roof. Zigzags are usually used on metal roofing, and the manufacturers usually have brackets premounted on the roof just for that.”
Electric mats, which are flat heaters, also are used on roofs. The choice of using zigzag tape or mats can depend on the architecture, according to one mat manufacturer.
“Normally, we solve problem areas where snow accumulates,” said Stephan Irgens, president, Electroplastics, which patented a self-regulating heating element used in the company’s mat products. “Some people put flat heaters on the roof underneath the shingles or underneath the metal roof. Others use tape in a zigzag design. Yet, so many of today’s construction projects are sophisticated, and the roofs are in all sorts of forms and shapes. That can cause problems if you don’t have a ‘cold roof’—one that is ventilated with insulation down to the ceiling. In lots of today’s construction, the roof is the ceiling. And you can have heat leakages up to the roof, which melts snow, converting it to water, causing ice damming. If you look at the roofs on winter sports places, you see the zigzag pattern of the electric tape. We put our mats flat on the roof, and our flat heater transmits heat better to a flat surface.”
Sidewalks in colder areas often are heated by electric heat systems. Their installation requires care and attention by contractors.
“The layout of the electric heat mats is critical,” Cisewski said. “Say you have a concrete driveway. A lot of times, there is customizing that has to be done in order to obtain the right dimensions of heat mass based on the manufacturers’ recommendations. If you have 25 feet of driveway that is 12 feet wide, you have to make sure the mats are 6 inches from each side. You can’t put them to the edge.
“And after you lay down the mats, you have to be there for the concrete pour. It can get rough when pouring. When they are dumping concrete, they are just dumping concrete. If the concrete cuts the mats or a wire, then the mat is no good. If there’s a break, we’d have to rip that concrete up,” he said.
In private homes and other types of housing, supplemental baseboard heat—zonal electric baseboard heaters—often are used. They contain electric heating elements encased in metal pipes, surrounded by aluminum fins to aid heat transfer, which run the length of the baseboard and are controlled by thermostats located within each room. The advantage is they allow for and supply individual room control.
“We’re looking at two residential jobs,” McCluskey said. “One project has floor-to-ceiling windows, so they want to put electric baseboard heat in front of those, at all perimeter north-facing window walls. That’s an example of a situation where normal heat pumps or rooftop heating and ventilating equipment can’t handle the heat loss through a large window opening.”
Baseboard heaters also can be used in toe spaces in kitchens and bathrooms, in multiunit dwellings such as dormitories, or for vacation homes.
“Several of my customers own a large number of rental properties, and the cost of installing a forced hot air or forced hot water system is too expensive. They don’t want to invest in boiler systems, which they don’t have to do if they use electric heat. That’s one of its advantages,” said Robert Jenkins, president, Jenkins Electric Inc., Rochester, N.H. “Interest in baseboards has increased in the last few years. I’ve been in business for 25 years, and everyone shied away from using electric heat because of the expense. But the new products are more efficient, and with renovations, it is a lot cheaper than going forced hot air or forced hot water system.”
Another form of electric heat is electrical underfloor heating or radiant heating systems, used in both commercial and domestic applications. Current flows through a conductive heating material. With high-voltage radiant heating systems, line voltage (110V or 230V) current flows through the heating cable. For low-voltage radiant heating systems, line voltage is converted to low voltage (8–30V) in the control unit that contains a step-down transformer. The voltage is applied to the heating element. The heated material heats the flooring until it reaches the proper temperature set by the floor thermostat.
While in the majority of commercial applications, hydronic rather than electric heat is the chosen system, use of electric heat under floors is a growth area for residences, according to several contractors and confirmed by Lawrence Drake, executive director, Radiant Panel Association (RPA).
“As we are becoming more affluent, we are more demanding regarding our amenities and comforts,” Drake said. “An electric system is often installed as a comfort amenity. What has really changed is its use in the bathroom. That used to be a utility place. But today, people are installing tile and stone floors. Since those surfaces are cold, it’s a natural match to have an electric radiant system because it doesn’t involve tying into the main house heating system, nor does it require any special adaptations.”
Ceramic tiles are the most common and effective floor covering for radiant floor heating because they conduct heat well and add thermal storage. According to 2006 figures of Floor Covering Weekly, there has been a 36.7 percent increase in sales of ceramic tile flooring.
“The floor covering industry, especially the stone and tile industry, has discovered that it makes their products much more attractive. Actually, we’ve tried to attract their attention for years, and it’s only been in the last few years that they have noticed,” Drake said.
In fact, according to the RPA annual sales reports, sales of radiant heat tubing increased yearly from 1990 to 2005. They declined 1.1 percent in 2006 (at press time, numbers for 2007 had not yet been calculated). But in that same year, housing starts also declined by almost 13 percent, which impacted radiant heating sales. Since electric heat products share in the growth of underfloor radiant heat, electrical contractors that specialize in remodels or residential work could direct marketing efforts to take advantage of that trend.
“A few years ago, at trade shows, you’d see a couple of electric radiant systems. And now there are all kinds of them, and the booths are packed,” Drake said. “The downside is that the building industry has slowed. But when you have a slowdown in the building industry, you usually have an increase in remodeling. People usually remodel their bathrooms and kitchens, so there’s a real market there. It’s easier to remodel with electric rather than with gas. The electric cables just go down in the thin-set mortar of the electric element. No real modifications need to be made to the structure.”
Even though electric heat is usually supplemental, in these days of calls for increased energy efficiency, some entities are encouraging its use.
“Electric utilities in our area are starting to give incentives in the form of rebates or lower electrical rates,” Cisewski said.
For example, the Wright-Hennepin Cooperative Electric Association, Rockford, Minn., offers incentives for the use of heat pumps, geothermal heat pumps, off-peak programs and underfloor radiant heat. Other cooperatives, such as Great Lakes Energy, a Touchstone Energy Cooperative in Michigan, and Clarke Electric Cooperative Inc., Iowa, offer similar incentives.
“We’re a power company and a rural electrical cooperative, and we want to pass along incentives to purchase products that are energy efficient. That’s good for the customer and for us,” said Joyce Neil, Clarke Electric Cooperative Inc. While installation of some of the systems—especially the energy-efficient geothermal systems usually handled by heating contractors—don’t require the skills of electrical contractors, others do and could be used in marketing efforts by interested contractors.
Utilities in metropolitan areas and those owned by investors, rather than cooperatives, favor other sources of energy.
“We don’t offer electric heat programs,” said Kim Sherman, product portfolio manager, Xcel Energy, a utility with headquarters in Minneapolis and offices in five other states. “We offer gas rebates because the cost of gas is a lot cheaper than the cost of electricity. With cooperatives, which are usually in rural areas that might not have access to natural gas, electric heat might be cheaper than using propane. But in the metro areas of the Midwest and the states that we serve, natural gas is less expensive than electric and is the predominant heating source, unless you are talking about geothermal heat pump systems.”
Electric heat’s cost dictates its popularity. While it is not perfect, its value as a supplemental system can’t be denied.
CASEY, author of “Kids Inventing! A Handbook for Young Inventors” and “Women Invent! Two Centuries of Discoveries that have Changed Our World,” can be reached at firstname.lastname@example.org or www.susancaseybooks.com.