The Heat is On

"Tankless hot water heaters are becoming better known to contractors and homeowners alike as the nation's energy woes become more apparent," says Maryke Gillis, marketing manager for Controlled Energy Corp. in Waitsfield, Vt. "The situation is making people more aware of being efficient with energy usage."

When that efficiency is coupled with the customer's ability to instantly draw on an unlimited supply of hot water, the reasons for the growth are apparent.

Go Tankless
Popular in Japan and Europe for decades, tankless water heater systems feature a heating unit that is activated by the flow of water when a hot-water valve is opened. Once activated, the heating unit delivers a constant supply of hot water until it is turned off. Only the tankless water heater's output affects the rate of heated water that is received. The units can be powered by electricity, gas or propane.

The benefits of such a unit are diverse, says Tom Massimin, president of Houston-based Hot Water LLC. A key one is energy savings. Because traditional tanks continually heat water (and then let it cool) to have some ready when needed, the gas pilot light remains burning, using energy even when the unit is idle. On-demand tanks don't require constant heating. Massimin estimates that tankless water heaters can save approximately 50 percent in hot-water heating costs over traditional water tanks.

"But in addition to saving energy and providing endless hot water, the units save space because they are so compact," Massimin says. "They can be put in places that are smaller than hot-water tanks require." Typically, they are hung on an interior or exterior wall, opening up floor space for other needs. Tankless water heaters also last longer because they don't store water that can corrode the metal or cause sediment buildups.

Heater Types
Tankless water heaters can be installed as whole-house models, supplying hot water from a central location, or as point-of-use models. Typically, whole-house models are used, and they are sized for the application, Gillis says. A point-of-use heater is used in locations where the water is a long way from the heater, such as a remote sink, allowing the water to cool down before reaching the site.

Sizing typically is determined by how many showers may be running at one time. "Most homes can use a standard unit that supplies one shower at a time, along with a sink," Gillis says. "But if your customers have two teenagers who have to shower each morning while getting ready for school, they'll need a larger size." The U.S. Department of Energy provides a chart of flow rates for various appliances to determine the needed size (see How to Choose the Right Size). All units have efficiency ratings, so contractors can gauge which unit is efficient for a customer's area.

Common Applications
Tankless water heaters are a strong option for vacation homes, Massimin notes, as occupants don't have to turn off the pilot light when they leave and turn it back on and wait for a tank of water to heat up before using it. The heaters also can be used in retrofit applications, but replacing an electric water heater can be expensive because the electrical service will have to be upgraded due to the high demand for electricity, he says. Gas units can be retrofit more easily.

"Retrofits require that contractors do their homework to make them work," Gillis says. "The product requirements need to be understood. The correct model has to be used, and the home's system has to be adapted properly."

Four key elements are necessary for a proper installation, she says.

• Gas heaters must be vented properly;
• A properly sized gas line must be used;
• Water lines must be sufficient to flow the right amount of water; and
• The combustion air requirements for the heater to function properly must be considered.

These rules often are skirted by professionals. Massimin says that about one-third of his business comes from cleaning up other installers' mistakes (see Key Installation Errors).

With proper installation, tankless water heaters offer many significant benefits that homeowners are beginning to understand, so plumbing contractors—no matter where they're located or which applications they specialize in—should be aware of them, Massimin says.

"I expect the trend to be toward more tankless heaters," he says. "There are getting to be more available products, consumers are more educated, the benefits are apparent, and costs are going up on gas and electricity. Contractors should learn about them, because they represent the future."