Tankless water heater not sensible for every home
May 26, 2009
I have a 12-year-old electric water heater and am thinking of
switching to a tankless water heater. I read they can reduce energy
costs and I'm wondering if that's true.
It's true that tankless, whole-house water heaters can save money
because they heat water on demand, rather than heating, reheating and
storing water. But there are some drawbacks if you're thinking of one
to replace an existing water heater.
For starters, electric tankless models require a large amount of
electricity quickly to heat water. Most are rated at 100 amps or
higher.
Roger Heasley, manager at Grover Electric and Plumbing Supply in
Vancouver, said they require three, 40 amp, double pole circuits, which
would most likely require an upgrade to a home's electrical panel,
adding considerably to the installation cost. Even switching to a gas
tankless heater could mean an added expense of new gas piping and
venting.
DuWayne Dunham, Clark Public Utilities energy counselor,
concurred.
"When electric tankless water heaters are operating they cost three or
more times as much as a traditional electric water heater costs to heat
water," Dunham said.
Operating a 100 amp appliance for one hour — the estimated average
daily use of electric tankless water heaters — costs $1.84 in
electricity in Clark County, Dunham said. By comparison, a traditional
water heater that serves a family of four will cost $1.21 a day to
operate.
The final kicker may be the cost of the units themselves.
High-efficiency traditional gas or electric water heaters will cost
about $400, while a whole house tankless water heater will be in the
$1,200 to $1,300 range, not including installation, according to
Heasley.
New construction
A gas unit in new construction is another story.
Keith Schlect of Schlect Plumbing in Battle Ground installs gas
tankless water heaters for Vancouver's New Traditions Homes.
"They've designed their homes so they fit on an outside wall and are
easily vented outside," he said. "People who have them in new
installations are happy with them, but as a retrofit it would have to
be easy to vent and the gas supply would have to be already
there."
The Energy Star program estimates that gas tankless water heaters that
meet its standards will save about $100 a year on gas bills for a
typical family. Energy Star-rated gas units also qualify for a federal
energy tax credit of up to $1,500.
"In new construction, a new addition or in homes with low water use,
tankless water heaters make more sense," Dunham said. "In most cases,
we wouldn't recommend them in a retrofit situation."
