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Water Heaters - Solar,
Tankless, Storage
When it comes to plumbing,
your water heater is one of the most
important items that contribute to your
overall comfort and safety. The hot water
generated by your water heater allows you
to take a warm shower, clean and sanitize
your dishes all within seconds. Continue
reading for more helpful information on
selecting a new water heater, the numerous
types of water heaters and more.
Selecting a New Water
Heater Summary: This fact sheet will
help you select an energy-efficient water
heater for your home. To view
illustrations, you can download the PDF
version (PDF
150 KB ) of this fact sheet (
Download Acrobat Reader ). See 'Source
List' below for more publications and Web
sites on related topics, which aren't
included in the PDF version. Many
homeowners wait until their water heater
fails before shopping for a replacement.
Because they are in a hurry to regain
their hot water supply, they are often
unable to take the time to shop for the
most energy-efficient unit for their
specific needs. This is unfortunate
because the cost of purchasing and
operating a water heater can vary greatly,
depending on the type, brand, and model
selected and on the quality of the
installation. To avoid this scenario, you
might want to do some research now before
you are faced with an emergency purchase.
Familiarize yourself today with the
options that will allow you to make an
informed decision when the need to buy a
new water heater arises.
Types of Water Heaters
Within the last few years,
a variety of water heaters have become
available to consumers. The following
types of water heaters are now on the
market: conventional storage, demand, heat
pump, tankless coil, indirect, and solar.
It is also possible to purchase water
heaters that can be connected to your
home's space-heating system.
Storage Water Heaters
A variety of fuel options
are available for conventional storage
water heaters electricity, natural gas,
oil, and propane. Ranging in size from 20
to 80 gallons (75.7 to 302.8 liters),
storage water heaters remain the most
popular type for residential heating needs
in the United States. A storage heater
operates by releasing hot water from the
top of the tank when the hot water tap is
turned on. To replace that hot water, cold
water enters the bottom of the tank,
ensuring that the tank is always full.
Because the water is constantly heated in
the tank, energy can be wasted even when
no faucet is on. This is called standby
heat loss. Newer, more energy-efficient
storage models can significantly reduce
the amount of standby heat loss, making
them much less expensive to operate. To
determine the most energy-efficient model,
consult the EnergyGuide label required on
storage water heaters. EnergyGuide labels
indicate either the annual estimated cost
of operating the system or energy
efficiency ratings.
Demand Water Heaters
It is possible to completely eliminate
standby heat losses from the tank and
reduce energy consumption 20% to 30% with
demand (or instantaneous) water heaters,
which do not have storage tanks. Cold
water travels through a pipe into the
unit, and either a gas burner or an
electric element heats the water only when
needed. With these systems, you never run
out of hot water. But there is one
potential drawback with most brands of
demand water heaters -- limited flow rate.
Typically, demand heaters provide hot
water at a rate of 2 to 4 gallons (7.6 to
15.2 liters) per minute. This flow rate
might suffice if your household does not
use hot water at more than one location at
the same time (e.g., showering and doing
laundry simultaneously). To meet hot water
demand when multiple faucets are being
used, demand heaters can be installed in
parallel sequence. Although gas-fired
demand heaters tend to have higher flow
rates than electric ones, they can waste
energy even when no water is being heated
if their pilot lights stay on. However,
the amount of energy consumed by a pilot
light is quite small.
Kevin Shaw Plumbing Inc. recommends and
installs
Rinnai Continuum demand gas
water heaters. Rinnai Continuum
provides never-ending hot water to
households 24 hours a day at the rate of
up to 8.5 gallons per minute. This
unique feature allows homeowners the
luxury of using multiple hot water sources
at once without any loss of temperature
consistency. Because Rinnai Continuum is
not limited by capacity, as are typical 50
and 75 gallon tanks, today’s 70+ gallon
bathtubs can be filled again and again
without penalizing the other hot water
needs in the home. Homes with a Rinnai
Continuum can run a washing machine,
dishwasher and shower simultaneously
without worrying about hot water running
out at any source. Rinnai Continuum is
up to 50 percent more energy efficient
than a traditional natural gas water
heater and up to 70 percent more efficient
than an electric water heater. Whereas
40-gallon tanks require 16 sq. ft. of
floor space and usually last around 10
years, Rinnai Continuum is a compact wall
mounted unit with a life expectancy of 25
years. Because the Continuum does not
require a tank, the risk of tank-type
water heater ruptures is eliminated.
Rinnai Continuum can be set to operate at
exact user-specifiable temperatures via
the digital and easy-to-use control pad
placed in multiple locations of a home.
This is an extremely important feature in
households with small children and elderly
individuals to help prevent scalding
accidents. Rinnai Continuum also offers
flexibility in its wall-mounted locations.
Should the user prefer to mount the unit
indoors, it safely uses no indoor make-up
air and vents directly to the atmosphere.
However, a unique advantage of Rinnai
Continuum is its ability to be mounted on
the exterior of a house, completely
removing a combustible device from the
home and freeing up valuable floor-space.
Additionally, the unit can be mounted in a
recessed box, flush-mounted and painted or
textured to match the external façade.
Heat Pump Water
Heaters
Heat pump water heaters use
electricity to move heat from one place to
another instead of generating heat
directly. To heat water for homes, heat
pump water heaters work like refrigerators
in reverse. Heat pump water heaters can be
purchased as integral units with built-in
water storage tanks or as add-ons that can
be retrofitted to an existing water heater
tank. These systems have a high initial
cost. They also require installation in
locations that remain in the 40-degree to
90 degree F (4.4 degrees to 32.2 degrees
C) range year-round and contain at least
1000 cubic feet (28.3 cubic meters) of air
space around the water heaters. To operate
most efficiently, they should be placed in
areas having excess heat, such as furnace
rooms. They will not work well in a cold
space.
Tankless Coil and
Indirect Water Heaters
A home's space-heating
system can also be used to heat water. Two
types of water heaters that use this
system are tankless coil and indirect. No
separate storage tank is needed in the
tankless coil water heater because water
is heated directly inside the boiler in a
hydronic (i.e., hot water) heating system.
The water flows through a heat exchanger
in the boiler whenever a hot water faucet
is turned on. During colder months, the
tankless coil works well because the
heating system is used regularly. However,
the system is less efficient during warmer
months and in warmer climates when the
boiler is used less frequently. A separate
storage tank is required with an indirect
water heater. Like the tankless coil, the
indirect water heater circulates water
through a heat exchanger in the boiler.
But this heated water then flows to an
insulated storage tank. Because the boiler
does not need to operate frequently, this
system is more efficient than the tankless
coil. In fact, when an indirect water
heater is used with a highly efficient
boiler, the combination may provide one of
the least expensive methods of water
heating.
Solar Water Heaters
Through specially designed
systems, energy from the sun can be used
to heat water for your home. Depending on
climate and water use, a properly
designed, installed, and maintained solar
water heater can meet from half to nearly
all of a home's hot water demand. Two
features, a collector and a storage tank,
characterize most solar water heaters.
Beyond these common features, solar
water-heating systems can vary
significantly in design. The various
system designs can be classified as
passive or active and as direct (also
called open loop) or indirect (also called
closed loop). Passive systems operate
without pumps and controls and can be more
reliable, more durable, easier to
maintain, longer lasting, and less
expensive to operate than active systems.
Active solar water heaters incorporate
pumps and controls to move heat-transfer
fluids from the collectors to the storage
tanks. Both active and passive solar
water-heating systems often require
conventional water heaters as backups, or
the solar systems function as preheaters
for the conventional units. A direct solar
water-heating system circulates household
water through collectors and is not
appropriate in climates in which freezing
temperatures occur. An indirect system
should not experience problems with
freezing because the fluid in the
collectors is usually a form of
antifreeze. If you are considering
purchasing a solar water-heating system,
you may want to compare products from
different manufacturers. The Solar Rating
and Certification Corporation (SRCC -- see
Source List at the end of this
publication) provides a benchmark for
comparing the performance of some solar
water heating systems. The SRCC publishes
performance ratings of both solar
water-heating systems and individual solar
collectors. These published ratings are
the results of independent, third party
laboratory testing of these products. All
systems and collectors that have been
certified by the SRCC will bear the SRCC
label. Keep in mind, though, that simply
having an SRCC label does not imply that
the product has a superior performance.
Carefully compare SRCC label information
on different brands and models to ensure
that you are fully aware of projected
performance. The Florida Solar Energy
Center (FSEC -- see Source List) also
provides information on solar
manufacturers and contractors. It also
maintains solar equipment testing
facilities and publishes performance
ratings for solar water heating systems.
Just choosing a solar water heater with
good ratings is not enough, though. Proper
design, sizing, installation, and
maintenance are also critical to ensure
efficient system performance. Although the
purchase and installation prices of solar
water heaters are usually higher than
those of conventional types, operating
costs are much lower. For more information
about solar water-heating systems, contact
the Energy Efficiency and Renewable Energy
Clearinghouse (EREC -- see Source List).
Criteria for
Selection
As with any purchase, balance the pros and
cons of the different water heaters in
light of your particular needs. There are
numerous factors to consider when choosing
a new water heater. This publication has
already described different system
configurations. Some other considerations
are capacity, efficiency, and cost.
Determining Capacity
Although some consumers base
their purchases on the size of the storage
tank, the peak hour demand capacity,
referred to as the first-hour rating (FHR)
on the EnergyGuide label, is actually the
more important figure. The FHR is a
measure of how much hot water the heater
will deliver during a busy hour, and it is
required by law to appear on the unit's
EnergyGuide label. Therefore, before you
shop, estimate your household's peak hour
demand and look for a unit with an FHR in
that range. Gas water heaters have higher
FHRs than electric water heaters of the
same storage capacity. Therefore, it may
be possible to meet your water-heating
needs with a gas unit that has a smaller
storage tank than an electric unit with
the same FHR. More efficient gas water
heaters use various non-conventional
arrangements for combustion air intake and
exhaust. These features, however, can
increase installation costs.
Rating Efficiency
Once you have decided what
type of water heater best suits your
needs, determine which water heater in
that category is the most fuel efficient.
The best indicator of a heater's
efficiency is its Energy Factor (EF),
which is based on recovery efficiency
(i.e., how efficiently the heat from the
energy source is transferred to the
water), standby losses (i.e., the
percentage of heat lost per hour from the
stored water compared to the heat content
of the water), and cycling losses. The
higher the EF, the more efficient the
water heater. Electric resistance water
heaters have an EF between 0.7 and 0.95;
gas heaters have an EF between 0.5 and
0.6, with some high-efficiency models
around 0.8; oil heaters range from 0.7 to
0.85; and heat pump water heaters range
from 1.5 to 2.0. Product literature from
manufacturers usually gives the appliance
s EF rating. If it does not, you can
obtain it by contacting an appliance
manufacturer association (see Source
List). Some other energy efficiency
features to look for are tanks with at
least 1.5 inches (3.8 centimeters) of foam
insulation and energy efficiency ratings
shown on the EnergyGuide labels.
Comparing Costs
Another factor uppermost in
many consumers' minds is cost, which
encompasses purchase price and lifetime
maintenance and operation expenses. When
choosing among different models, it is
wise to analyze the life-cycle cost -- the
total of all costs and benefits associated
with a purchase during its estimated
lifetime. More information on conducting
life cycle cost analyses is available from
EREC. Units with longer warranties usually
have higher price tags, though. Often, the
least expensive water heater to purchase
is the most expensive to operate.
Source List
The following organizations
and publications provide more information
on hot water energy efficiency. This list
does not cover all the available books,
reports, and articles on hot water energy
efficiency. Also contact your state and
local government energy offices for
additional information on rebate or
incentive programs.
Energy Efficiency and
Renewable Energy Clearinghouse (EREC)
P.O. Box 3048
Merrifield, VA 22116
Phone:(800) 363-3732
Fax: (703) 893-0400
Consumer Energy Information Web site
E-mail: doe.erec@nciinc.com
Energy experts at EREC provide free
general and technical information to the
public on a wide spectrum of topics and
technologies pertaining to energy
efficiency and renewable energy.
American Council for an Energy-Efficient
Economy (ACEEE)
1001 Connecticut Avenue, NW, Suite 801
Washington, DC 20036
Phone: (202) 429-8873 or (202) 429-0063
ACEEE provides general and technical
information on energy efficiency,
including these publications: The
Consumer Guide to Home Energy Savings,
The Most Energy-Efficient Appliances,
and Saving Energy and Money with Home
Appliances .
Association of Home Appliance
Manufacturers (AHAM)
Suite 402
1111 19th Street, NW
Washington, DC 20036
Phone: (202) 872-5955
Fax: (202) 872-9354
AHAM provides energy efficiency
information for specific brands of major
appliances. The association also runs a
certification program for certain types
of appliances.
Florida Solar Energy Center (FSEC)
1679 Clearlake Road
Cocoa, FL 32922-5703
Phone: (407) 638-1000
Fax: (407) 638-1010
E-mail: info@fsec.ucf.edu
FSEC is an alternative energy center.
The FSEC staff conducts research on a
range of solar technologies, offers
solar energy workshops, and distributes
many free publications to the public.
Gas Appliance Manufacturers Association,
Inc. (GAMA)
1901 North Moore Street, Suite 1100
Arlington, VA 22209
Phone: (703) 525-9565
Fax: (703) 525-0718
E-mail: information@gamanet.org
GAMA has information on residential gas
appliances and equipment, electric and
oil-fired water heaters, and oil- fired
warm air furnaces.
Solar Rating and Certification
Corporation (SRCC)
c/o FSEC
1679 Clearlake Road
Cocoa, FL 32922-5703
Phone: (407) 638-1537
Fax: (407) 638-1010
E-mail: srcc@fsec.ucf.edu
SRCC publishes the thermal-performance
ratings of solar energy equipment. The
SRCC offers a directory of certified
solar systems and collectors as well as
a document (OG-300-91) that details the
operating guidelines and minimum
standards for certifying solar hot-water
systems.
Reading List Books
and Reports
Consumer Reports 1992 Buying Guide Issue ,
Consumers Union of the United States,
Inc., 101 Truman Avenue, Yonkers, NY
10703, December 1991. The Water Heater
Workbook: A Hands-on Guide to Water
Heaters , published by Elemental
Enterprises, P.O. Box 928, Monterey, CA
93942, 1992.
Articles
"Heat Pump Water Heaters in Hawaii -- The
Quiet Revolution," Plumbing Engineering ,
pp. 36 40, September 1994. "Product Guide:
Hot Water Heaters/Boilers," Energy User
News , p. 28, January 1990. "Safer Water
Filters, Cheaper Water Heating Systems,
and More," Home Mechanix , p. 37, June
1993. "Solar Hot Water for the 90s," Solar
Today , p. 20, September 1991.
The National Renewable
Energy Laboratory (NREL), a DOE national
laboratory, produced this document for the
U.S. Department of Energy (DOE).
DOE/GO-10095-064
January 1995
Revised February 2000
NOTICE:
This report was prepared as an account of
work sponsored by an agency of the United
States government. Neither the United
States government nor any agency thereof,
nor any of their employees, makes any
warranty, express or implied, or assumes
any legal liability or responsibility for
the accuracy, completeness, or usefulness
of any information, apparatus, product, or
process disclosed, or represents that its
use would not infringe privately owned
rights. Reference herein to any specific
commercial product, process, or service by
trade name, trademark, manufacturer, or
otherwise does not necessarily constitute
or imply its endorsement, recommendation,
or favoring by the United States
government or any agency thereof. The
views and opinions of authors expressed
herein do not necessarily state or reflect
those of the United States government or
any agency thereof
If you are looking for a
water heater contractor in the San Gabriel
Valley, please call us
today at 626-359-1864 or complete our
online service request form.
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