Monday
Nov292004
Tankless Hot Water Heaters
Monday, November 29, 2004 at 06:42AM TIP OF THE DAY
Tankless Hot Water Heaters
Tankless Hot Water Heaters
The Rise of the Bottomless Hot Water Heaters
http://www.nytimes.com/2004/11/28/business/yourmoney/28water.html?oref=login&ex=1259384400&By KATE MURPHY
IN mid-lather, the shower's stream goes from hot to tepid to frigid. You endure an icy rinse, cursing through chattering teeth. It's a familiar aggravation, especially if you live in a household where more than one person needs to shower within a short period - or where the dishwasher and the washing machine are often in use.
But running out of hot water is a rare occurrence in homes in Western Europe and Japan, where tankless water heaters are the norm. These systems not only provide an endless supply of hot water, but they are also more energy-efficient than the cylindrical tank-style water heaters common in the United States.
Now facing increased fuel prices, more Americans are choosing tankless units, despite higher upfront costs. "The last time people in the U.S. seriously looked at this technology was during the last energy crunch" in the 1970's, said Richard Trethewey, the heating and plumbing expert for "This Old House," the PBS series. But tankless water heaters, also known as demand or instantaneous water heaters, didn't take hold then because they had relatively low flow rates. That means they could offer an inexhaustible supply of hot water, but only if the faucets were just half open.
"People like to get their hot water full blast," Mr. Trethewey said. But because of improved technology, the flow rates of tankless heaters have improved greatly in the last 10 years. And they have become even more energy-efficient.
"Demand water heaters save energy because they heat water on the fly," said Craig Drumheller, senior energy engineer at the National Association of Home Builders Research Center in Upper Marlboro, Md. Tank water heaters cycle on and off all day, keeping 30 to 50 gallons of water at around 120 degrees, but tankless units heat only the water flowing through them when someone opens a spigot. Because of such intermittent activity and the absence of a tank to corrode, tankless units tend to last 20 to 25 years, versus 8 to 10 years for a tank heater, according to the Energy Department.
Tankless heaters, essentially a labyrinth of heating coils within a briefcase-sized chamber, "are kind of like waterproof toasters," said Harvey Sachs, director of the buildings program at the American Council for an Energy-Efficient Economy in Washington, a nonprofit organization that conducts research for utility companies and federal and state environmental agencies.
But because tankless heaters have sophisticated microprocessors for regulating temperature and flow, they are priced considerably higher than toasters - or tank heaters. Depending on their capacity, whole-house units by makers like Bosch, Rinnai, Takagi and Seisco cost $350 to $2,500, or twice what comparable tank units cost. They are also more expensive to install in existing homes: gas units may require wider-than-usual vents, as well as larger gas pipes running to the meter, while electrical units may need an added circuit. Manufacturers of tank heaters say the steep start-up costs make it unlikely that tankless units will supplant their products.
Still, many people who have made the investment say it's worth it. Philip S. Diakun, a computer technician at Sun Microsystems in Phoenix, said the tankless heater he had installed two years ago has almost paid for itself by lowering his monthly gas bills 15 percent. He paid $650 for it, plus $350 for a plumber to install it in his 1,764-square-foot, two-bathroom house. The only retrofitting required was enlarging a vent. In addition to consuming less energy than his old tank unit, Mr. Diakun said, his tankless heater "saves space because it's smaller and hangs on the wall." Best of all, he said, "you never get in the position of having to wait after you wash dishes for the hot water tank to fill back up so you can take a shower."
Because Mr. Diakun's household consists of just him and his wife, Connie, he chose a tankless unit with a modest flow rate of two to four gallons a minute, depending on incoming water temperature. Since it rarely drops below freezing in Phoenix, the unit usually operates at the high end of the range, which is more than enough to run a shower and dishwasher simultaneously. "If you live somewhere really cold or have a lot of kids and can't take consecutive showers, then you'd need more capacity," he said.
Helen Clark, a homemaker in Houston, recently got a gas-powered tankless heater that provides six to nine gallons a minute for her family of six. A native of Scotland, she grew up with tankless units. "I have little patience for running out of hot water," she said. In remodeling her 2,500-square-foot, 2½-bathroom house, she jumped at the chance to get rid of her old tank heater.
The new unit cost $2,000 and the installation an additional $3,000 because she had pipes rerouted to put the unit in her attic, closer to the bathrooms. "It was worth every penny," Ms. Clark said. "We used to run out of hot water all the time, and now we never do; even if I'm doing the wash and more than one person is taking a shower."
TO figure the heater capacity your home needs, add the flow rates of all faucets and appliances that draw hot water during peak times like the morning, when you're washing the breakfast dishes and everyone else wants to take a shower.
Colin Bull, a plumber who installed tankless water heaters in his native England and now installs them in Houston, advises consumers to look for units with a "temperature rise" that can heat incoming water on the year's coldest day to at least 105 degrees - a comfortable shower temperature - without cutting the flow rate to an unacceptable level. If the incoming water temperature dips to 35, a temperature rise of 70 would be needed at the desired flow rate.
James Pinkerton of Wapello, Ill., says that because his water comes from a well, his electric tankless heater performs the same even when the outside temperature is below zero. "It comes in at the same temperature year round," he said. An operations manager at a nuclear power plant, he paid $400 for his unit, which provides two to two and a half gallons a minute. He installed it himself two years ago in the shop behind his house where he restores vintage trucks. "I use a lot of hot water to wash parts, and hot water is better for washing down the trucks," he said. He also showers in the shop's bathroom if his two teenage daughters have used all the hot water in his home.
"As soon as the tank heater in the house goes, I'm putting in a tankless," he said.