Water Heaters - Know Before You Buy

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.
Within the last few years, a variety of water heaters have become
available to consumers. The following types of water heaters are the
most common in our area of the country; conventional storage and
demand.  The heat pump, tankless coil indirect and solar are more
common in the areas of the country where basements are much more
common.  

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
Energy Guide label required on storage water heaters. Energy Guide
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
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.

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. Some other considerations
are capacity, efficiency, and cost.

Determining Capacity
Although some consumers base their purchase on the size of the
storage tank, the peak hour demand capacity, referred to as the first
hour rating (FHR) on the Energy Guide 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 Energy Guide 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. 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 Energy Guide 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.
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Water Heaters
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