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GAZETTE Newspapers
By: Arthur S. Lazerow
High Efficiency Water Heaters
Question: Mary Ann from Gaithersburg emailed last week:
“In the Gazette article 3/15/06 you discussed replacing the hot
water heater. With the cost of energy skyrocketing why did you
not mention the European style "on demand" units?”
Answer: What a terrific and timely question! Thank you, Mary
Ann. With the cost of gas, oil and electricity moving ever
higher and deregulation of the electric utility companies in
Maryland scheduled for this summer, energy conservation should
be of concern for everyone who pays a utility bill. The
February 28 Ask Mr. Home Inspector article discussed the
SEER 13 high efficiency air conditioning systems, which became
the standard for manufacturers starting January 2006, although
lower rated (and cheaper) equipment can be installed until
inventories are exhausted.
The first consideration is efficiency of currently installed and
properly operating water heaters. Newer water heaters, of
course, operate more efficiently than older ones, not because of
burner or electric element efficiency, but because they are
better insulated and therefore loss less heat through its outer
shell. These newer heaters are insulated up to a standard of
R-16. They should not receive an auxiliary insulation jacket
under any circumstance. An insulating blanket causes premature
rusting of the outer jacket, hides leaks and has been found to
restrict combustion airflow to the gas burner, potentially
creating a carbon monoxide problem.
However, engineers in the energy conservation area do recommend
an auxiliary insulation jacket around older water heaters, which
may have interior insulation rated as low as R-7. Installation
should be done carefully by a plumber.
Another strategy to boost energy efficiency is to install a
tempering tank. This is a water tank installed in a warm area
of the home that uses the heat of the room to raise the
temperature of the water prior to its entry into the primary
water heater. Thus, less energy is required to produce domestic
hot water. Neat idea, but may be impractical in many homes.
Now for new energy efficient water heating systems. Water
heaters have a statistical life span of 10 to 15 years, although
some fail prematurely and some chug along into their old age.
As I wrote last the March 14 column, waiting one day too long to
replace an aged water heater causes consternation. At some
point, if the water heater is 17 or 18 years in service,
consider replacement. If an older water heater begins to
produce less hot water, needs repair or begins to leak, replace
it.
The most commonly installed higher efficiency water heater is
called a “Power Vent” gas water heater. Its name comes from the
fan that assists venting of combustion gases. Rerouting
combustion gases for a pass through a second heat exchanger
removes over 90% of the heat produced by combustion, an
improvement over the 65% efficient equipment that is the norm.
Most power vented water heaters are eligible for the federal tax
credit effective January 1, 2006. See the website of the Gas
Appliance Manufacturing Association gamanet.com.
Heat pump water heaters have not been popular, due to cost
considerations. Newer equipment, however, is twice as efficient
as an electric tank-type water heater in an all-electric home
and the cost has recently moderated. A heat pump accumulates
the heat in its installation space and uses this heat to raise
the water temperature from the 50-degree level up to 120-140
degrees. Unfortunately, the system also expels cool air into
the space, which is fine during the summer but will cause a
slight increase in winter heating costs, depending on the
location of the heat pump water heater.
Solar water heating is available for any climate. It utilizes
storage tanks and solar collectors to maximize the power of
sunlight. Often, the storage tank has a back-up water heating
system. Since our area has winter freezing temperature, an
indirect circulation system would be most appropriate. Pumps
circulate a non-freezing heat transfer liquid through the solar
collectors and a heat exchanger, which heats the water supply
for the home.
Finally, tankless water heating has limited application, but is
very useful where only a small amount of hot water is needed,
such as in a one bath, one kitchen dwelling. Also called
instant hot water, the tankless system produces hot water on
demand. They are physically smaller, so they can fit into
bathrooms or kitchens. Generally, a tankless system will serve
one area. Although expensive to purchase and install, from an
energy conservation viewpoint, tankless systems are outstanding,
since they do not have a tank full of water to maintain at the
designated temperature.
The information above is intended to present the energy
efficient alternative for residential water heating. Depending
on the system chosen, there may be federal tax credits
available. The final decision on which system works best for a
particular application will be made with a knowledgeable plumber
or mechanical engineer. This is not an issue that can be
handled without professional guidance.
Have a question relating to a housing or environmental issue?
To contact Mr. Lazerow, click on “Contact Us” at
Albaninspect.com. Mention “Gazette Newspapers” in your
question. Every question will be answered and some will be
included in this column.
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