Launch Slideshow

On Demand

As more builders look for energy-efficient technology, tankless water heaters may one day be the norm, rather than the exception, in homes nationwide.

On Demand

As more builders look for energy-efficient technology, tankless water heaters may one day be the norm, rather than the exception, in homes nationwide.

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    Grand Hall. The Eternal GU32 hybrid water heating system combines the best attributes of tank and tankless systems, with an inverted-infrared heat burner that uses thermal activation like a tank and flow activation like a tankless. The system uses a counter-flow design and multi-pass heat exchanger technology to maintain an 86% thermal efficiency rating with consistent pressure. The unit operates at a lower emission rate than traditional tank and tankless water heaters, says the company. The system’s nitrogen oxide emission is less than 5 parts per million. 877.934.7455. www.eternalwaterheater.com  
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    Stiebel Eltron. The electric Tempra whole-house series comprises six tankless water heater models, from 12 kW to 36 kW, that can be installed in homes with one to four bathrooms. The smallest capacity unit has one heating module, the mid-range models have two heating modules, and the largest capacity units have three heating modules, which are all wired back separately to the electric panel. The temperature and flow sensors feed their readings into the water heater’s microprocessor control, and the microprocessor prevents the water temperature from deviating from the set point. The tankless water heaters, which the company says are nearly 100% efficient, save 15% to 20% on water heating costs compared to a tank water heater. Energy factor: 0.99. 800.582.8423. www.stiebel-eltron-usa.com  
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    Chronomite. The electric Insta Flow point-of-use tankless water heaters are 98% efficient, says the firm. Digital microprocessor technology controls the temperature of the water, and the temperature can be pre-set to prevent scalding without mixing valves. The units come in three different capacities­—Insta Temp, Insta Flow, and Insta Flow Micro—and are also available in a wide range of models to fit the desired application. 800.447.4962. www.chronomite.com
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    Takagi. The gas-fired TK-3 Pro is designed to withstand space-heating and domestic recirculation systems in residential applications. It starts heating water at flow rates as low as 0.5 gallons per minute, but it can generate an unlimited supply of hot water at a maximum flow rate of 7 gallons per minute. The unit measures 13.8 inches wide and weighs 40 pounds. It can be installed inside or outside and can be direct-vented. Energy factor: Natural gas: 0.827; LP: 0.833. 888.882.5244. www.takagi.com
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    Rheem. The RTG-66DV gas direct-vent, tankless water heater is designed for homes with two or three bathrooms. The unit measures 25 1/2 inches high, 13 1/2 inches wide, and 10 inches deep. The concentric venting system simplifies installation by expelling the byproducts of combustion through a 3-inch exhaust pipe inside the 5-inch intake run. The unit can deliver water at a rate of 6.6 gallons per minute. Installers can connect multiple units to meet the needs of high-demand applications. The product uses either natural gas or liquid propane. Energy factor: 0.82. 334.260.1500. www.rheemtankless.com
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    Noritz. The Energy Star–rated N-0841MC tankless water heater yields 93% energy efficiency versus 60% of a typical tank water heater due to its Hybrid Super Heat Exchanger—a stainless and copper heat exchanger fused into one. The unit, which uses gas or propane, delivers up to 11.1 gallons per minute at a 35-degree temperature rise and 8.4 gallons per minute at a 45-degree temperature rise. Energy factor: 0.94. 877.986.6748. www.noritz.com
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    Rinnai. The R75Lsi delivers continuous hot water on demand up to 7.5 gallons per minute. The unit features a redesigned commercial-grade heat exchanger, an integrated condensate collector, an integrated digital temperature controller, and direct electronic ignition with no pilot light. The combustion unit is sealed, so it doesn’t use interior combustion air. Two units can be connected together without a control board. The whole-house unit measures 10 inches by 14 inches by 26 inches and weighs 46 pounds. The temperature can range from 98 to 140 degrees. Energy factor: 0.82. 678.829.1700. www.foreverhotwater.com
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    Eemax. The Series Four large-capacity electric tankless water heater is rated at 99% efficient. The whole-house unit features microprocessing temperature control. The flow activates each of the EX380T2T2’s heating elements in stages based on hot water demand. Thermostatic control delivers unlimited hot water at precise outlet temperature. Energy factor: 0.99. 800.543.6163. www.eemax.com
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    Bosch. The Bosch AquaStar 2700ES gas tankless water heater enables users to operate two to three hot water applications simultaneously. The unit delivers more than 7 gallons per minute. The product’s built-in power vent enables horizontal or vertical vent termination, and the unit offers direct, room-sealed electric combustion. The unit can plug into a 120V electrical outlet and uses natural gas or liquid propane. Energy factor: 0.83. 866.642.3199. www.boschhotwater.com

A range of capacities is available for both gas and electric models. Some units are designed for homes with multiple bathrooms, while others are suitable for smaller homes with a single shower.

Green builders also can select the most efficient models based on national recognitions and standards. Energy Star recently established a residential water heating program to recognize gas, whole-home tankless water heaters with an energy factor (EF) of 0.82 or better, gas condensing units with an EF of 0.80, and electric heat pump water heaters with an EF of 2.0. So far, however, Energy Star has not recognized electric tankless water heaters, which typically have an EF of 0.98 to 0.99 compared to 0.91 to 0.95 for an electric tank unit, because it is still a small market and the energy savings are too low, according to Energy Star.

Builders also can earn two points toward LEED certification if the gas unit has an EF of at least 0.80 or an electric tankless unit has an EF of 0.99. The National Green Building Standard awards points for whole-house tankless units that are either direct-vented or power-vented to improve indoor air quality and minimize contamination from combustion byproducts.

All of that efficiency, however, comes at a price. Banker estimates that most tankless water heaters cost two to two-and-a-half times more than a traditional tank model. Federal and local tax incentives and rebates, along with incentives available from many utilities, can help offset the sticker shock.

While the return on investment depends heavily on water usage and energy prices, homeowners can expect to recoup their initial investment in about four to six years. In addition, the life span of a tankless water heater is two to three times longer than a traditional water heater.

Infrastructure & Installation

While both gas and electric tankless water heaters are generally considered more energy efficient than tank models, builders should note that tankless units actually consume more energy than tank water heaters, but for shorter periods of time. To accommodate these significant surges of energy, gas units must be connected to a large gas line and electric models require extra breakers to support the heating modules in the system.