Product Spotlight: Comparing tankless water heaters

| by Teena Hammond

There's no end to the hot water with a tankless water heater — even if every sink and shower in the house is running at the same time. With a tankless water heater, water is only heated when needed, and this can result in big savings of up to 30 percent on water heating bills.

Traditional water heaters work by storing hot water — usually from 20 to 80 gallons, depending on the size of the unit — for later use. The water within a traditional gas, propane or electric water heater is continuously warmed to a pre-set temperature, so energy is used throughout the day to keep the water hot.

Heating water accounts for 30 percent of the average home's energy bill, so reducing the amount of energy used for this purpose by switching to a tankless unit can result in significant savings of up to $100 a year in an average household.

By switching to an on-demand tankless water heater, there is no need for a large storage tank for water. When a faucet or showerhead or other hot-water using device is turned on, water flows through the tankless water heater and through a heating element, either a gas burner or an electrical element, which warms the water.

There are a few cons to tankless systems. There is a slight lag time, since hot water isn't on standby. This can lead to water waste, while waiting for water to warm up after a faucet is turned on. An option to overcome that is placing a tankless system near where it will be used the most, such as the master bath. Or, additional, smaller units can be place in bathrooms that are far away from the main unit. This also overcomes another potential problem, which is that one tankless system only provides about two to 12 gallons of hot water a minute. If every shower in the house is turned on, this could cause a problem. Because although the hot water supply is unlimited, there would be less hot water going to each open faucet, resulting in water that is simply warm, rather than hot. Smaller additional units will take care of this issue.

Here is a comparison of tankless hot water heaters:

Manufacturer: Bosch

Power source: Natural gas/propane

Model: Therm C1050 ES

Gallons per minute: Delivers max of 10.5 gallons per minute

Thermal output: 199,000 BTU

Weight: 74 lbs.

Dimensions: H: 30.5" W: 17.875" D: 11.25"

Retail price: $2,350

This top-of-the-line Bosch model is suitable for indoor and outdoor installations. It includes an electronic ignition and patented burner design. It can also be used in solar thermal and recirculation applications. Come with a 15-year warranty and a 20-year+ life expectancy, allowing the unit to pay for itself with energy savings.


Manufacturer: Sylvan

Power source: Natural gas/propane

Model: JSW series, 12GPM

Gallons per minute: Delivers max of 12 gallons per minute

Thermal output: 109,999 BTU

Weight: 40 lbs.

Dimensions: H: 23" W: 15" D: 7"

Retail price: $1,500

The Sylvan series provides an on-board computer to give specific trouble codes on a color screen to alert homeowners of any problems. It works with natural gas or propane, and will pay for itself during its lifetime with the amount saved on energy bills. It includes an auto-electric pulse ignition, so there is no standing pilot light to worry about. There are also winter/summer auto-control settings to maximize energy consumption.


Manufacturer: General Electric

Power source: Natural gas/propane


Gallons per minute: Delivers max of 7.5 gallons per minute

Thermal output: 180,000 BTU

Weight: 49 lbs.

Dimensions: H: 22.875" W: 17.875" D: 9.625"

Retail Price: $1,449

The G.E. tankless hot water heater has a compact design that frees up floor space with a wall-mounted installation. It can be wall-mounted in many areas of the home. It offers energy savings of up to 25 percent compared to a standard 40-gallon gas tank model based on testing from the U.S. Department of Energy.


Manufacturer: Rinnai

Power source: Natural gas/propane

Model: RL94i (VB2735FFUD-US)

Gallons per minute: Delivers max of 9.4 gallons per minute

Thermal output: 199,000 BTU

Weight: 50 lbs.

Dimensions: H: 22.9" W: 14" D: 9.6"

Retail Price: $1,699

The R94LSi provides hot water for up to five plumbing and appliance outlets simultaneously and always at a consistent, pre-set temperature. This compact, interior-mount unit vents directly to the outside with a concentric venting system.

For more information, see our Water Heater Research Center.

Topics: Water Heaters

Companies: GE Appliances, Rinnai, Bosch

Teena Hammond
Teena Hammond has published more than 2,000 articles in People and W magazines, Women's Wear Daily, and in dozens of newspapers and books. She also wrote a home improvement, remodeling and decor column that ran in Gannett newspapers nationwide. She's interested in all things green and would love to hear from you with your story ideas.

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