Tankless Water Heater or Storage Type? Which Is
Right For You?
Having instantly available hot water at the fixture
when you reach for the faucet saves you not only time, but water as
well. You don’t have to stand there running water down the drain while
you wait.
Lots of folks have fixtures so far away from the
water heater that they turn on the hot water and go do something else
instead of standing there waiting. When they return the water is hot.
That means they have been running hot water down the drain. The energy
to heat water is much more expensive than the water itself. This is a
huge waste of energy and contributes to the emission of green house
gases as well. An instant hot water system eliminates this waste of
course.
Instant hot water systems can even result in
cleaner dishes! The leading cause of dishwasher problems is that the
water often is not hot enough to completely dissolve the dishwashing
detergent. By insuring your dishwasher gets hot water you will have
sparkling clean dishes.
There are a number of “instant” or “fast” hot water
pumping/distribution systems on the market, and it’s important to choose
the right system for your particular application. Some use pumps, some
rely on thermo-siphoning, and not all systems will work will all types
of water heaters.
Some of these systems manufactured by Laing,
RedyTemp, and others place a pump and valve combination at the fixture
furthest from the water heater. The system pumps the hot water in a big
loop, out of the water heater to the fixture, through the pump, through
the cold water piping back to the water heater. The pumps have very
slow pumping rates. When the valve between the hot and cold water lines
detects hot water it closes. This keeps the water at the valve at about
95 degrees.
The problem with this type of system is that it is
really a “luke-warm” system. Ninety five degrees is below the human
body temperature so it actually feels like cool water. Since you are
not starting with cold water and the pipe is full of luke-warm water, it
won’t take quite as long for the hot water to reach the fixture, but it
certainly is not instant hot water!
The pumping system is cycling on and off constantly
all day long, and so it keeps the piping (both hot and cold) full of
warmer than ambient temperature water. This makes the water heater work
harder, and uses significantly more energy than a standard plumbing
system. The pumps run for long periods too, so add that energy into the
mix.
These systems will not work with tankless water
heaters. Tankless water heaters require usually ½ gallon per minute or
more to being flowing through the heater before it will turn on. The
Laing and RedyTemp systems don’t pump enough water to turn on the
heaters.
Another type of system puts the pump at the water
heater and a valve at the fixture furthest from the water heater. The
pump creates a pressure difference between the hot and cold lines, and
so when the valves under the sink open the water flows through into the
cold water lines and back to the water heater inlet. The valves are
temperature controlled and close when they detect that 95 degree water.
The Grundfos system allows the placement of more than one valve, even
one for every fixture if so desired. Watts makes a similar system but
you only get to use one valve at one fixture. These types of systems
often include a clock timer with them so you can shut them off when you
aren’t going to use them. It can be a pain when the power goes off and
the clock gets screwed up.
Like the previous systems, these systems also keep
the hot and cold water lines full of warm water and thus waste
tremendous amounts of energy. As with the previously mentioned pumps,
these systems can not be used with tankless water heaters for the same
reasons.
If saving water and being energy efficient are
important to you then you will want to examine “Demand” hot water
systems. Demand systems deliver hot water rapidly to the fixtures upon
demand. When you want hot water you push a button, and the hot water is
pumped at high speed to the fixture. When the hot water reaches the
fixture the pump shuts off keeping hot water out of the cold water
pipes. Now you have instant hot water, nothing was run down the drain,
and you didn’t waste any heat energy keeping the pipes hot all the time.
Metlund makes a system called a D’mand system with
a number of models. They range in price from a little over $330.00 to
over $500, and have a number of accessories like using motion detectors
to turn on the pump. Metlund’s largest D’mand system will run most
tankless water heaters.
Chilipepper Sales has a demand system called the
Chilipepper Appliance. The Chilipepper Appliance has the most powerful
pump on the market, and will work with any tankless water heater. It
will in fact work with any storage type water heater as well. The
Chilipepper is the least expensive of the systems at $180.00. Since
demand systems only run for a few seconds each time they are used, they
use very little electricity. Typical systems use about $1.00 - $2.00
per year in electricity for the pump.
One of the best things about having a demand hot
water system is that whenever you use hot water, and you push the button
to start the pump, you will feel so darned good about not running all
that water down the drain.
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