Energy Adviser: Tankless gas water heaters can save cash

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If your gas water heater has been hissing along for 10 or 15 years, you might want to start thinking about a replacement before you wake up to a cold shower.

Given that heating water is the second-most expensive energy use in the average Pacific Northwest home, you'll want the replacement to be as energy-efficient as possible.

A tankless water heater may fit the bill.

"Anybody who has gas available should probably consider it," said Gary Heikkinen, a sales engineer for NW Natural, which has 63,000 residential customers in Clark County. "It's a very good and efficient way to heat water."

While electric tankless water heaters aren't generally recommended because of the higher cost to purchase and install, gas customers can often realize savings with a tankless water heater.

A typical storage tank gas water heater is 60 percent efficient, while tankless gas water heaters can be 80 percent or even 95 percent efficient.

"The real benefit is for those who have larger families. You don't have to worry about depleting the hot water if you have multiple hot showers back-to-back because you have an endless supply," Heikkinen said.

Tankless models heat water on demand, so they don't waste energy heating and reheating water sitting in a tank, Heikkinen said. A tankless heater carries less risk of water damage. Storage tank heaters can leak or rupture in as few as 10 years. A tankless water heater will only leak if there's a pipe-fitting failure, and will last 20 years or so.

That's a good thing, given that they cost a lot more than the typical tank. Tony Sarkinen, a Vancouver plumber who installs all kinds of water heaters, said his cost on the units runs between $1,000 to $1,500. But installation costs more, because although tankless water heaters take up little room, they require upgraded gas pipes, ventilation and electrical wiring.

For an average family of three or four people with an old gas water heater, it might cost $300 a year for hot water, Heikkinen said. A 95 percent efficient tankless gas water heater would cut the cost in half. A 67 percent efficient tank gas water heater might cut the cost to about $250, he said.

Sarkinen said the trick is to find the right fit for your family. Lots of people using hot water at the same time throughout the house may leave taps running cool.

Another factor in choosing a new gas water heater is how long it would take you to recoup your investment if you spend the extra money for a super-efficient tankless water heater.

"The price of natural gas continues to come down, so it's harder to pass the cost-effectiveness test," Heikkinen said.

Washington residents can get a $200 rebate from Energy Trust of Oregon for either a tank or tankless gas water heater. A storage-tank gas water heater must be 67 percent efficient to qualify, and the tankless must be at least 80 percent efficient. For more information, visit Energy Trust of Oregon. Enegry Adviser is written by Clark Public Utilities. Send questions to energyadviser@clarkpud.com or to Energy Adviser, c/o Clark Public Utilities, P.O. Box 8900, Vancouver, WA 98668.