May
2005
Tanked
Up
Is
a tankless water heater right for you?
We've
been getting a flurry of questions lately about tankless water heaters.
Tankless
water heaters are just what the name says-water heaters with no
holding tank. They heat water on demand rather than storing hot
water for use later.
A
large heating element in the unit heats water as it flows through
the unit.
These
appliances are common in Japan and Europe where they've been in
use many decades. They made their first appearance in the United
States about 25 years ago.
On
the surface, tankless water heaters seem like a great idea.
There is no wasted water while you wait for hot water to reach the
faucet. There's also no standby loss from the tank while it sits
day-in and day-out.
But
for the typical family, a tankless water heater will not meet normal
water heating needs.
The
output of most units is only two to three gallons of hot water per
minute. This means activities using hot water, like showering, laundry
or washing dishes can only be done one at a time. This doesn't fit
in the lifestyle of most busy households.
It
also takes a long time to fill a bathtub using a tankless unit.
If the unit is not a modulated type, water temperature drops as
demand increases.
The
more capacity, the higher a tankless water heater costs. Models
that can supply five gallons per minute can cost $1,000 or more.
And
wiring requirements of tankless water heaters are big. Some
can draw up to 28,000 watts! That's 117 amps, which may be
more than all the rest of the electrical use in the home combined.
The electrical service of the home will need to be large enough
to accommodate the extra load.
Because
tankless water heaters don't have standby losses, their energy factor
is relatively high-around 0.98. But super-insulated water heaters,
like the Marathon, approach that figure at 0.91. If you keep the
temperature of the water at 120 degrees, the Marathon is even more
competitive.
Standard
water heaters with an insulating wrap can also approach these energy
factors.
Weigh
the pros and cons very carefully before deciding on a tankless water
heater.
More
Information: Home
Energy Saver
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