Storage Water Heaters
water heaters, also known as tank water heaters, are the most
common type in use for both residential and commercial applications.
In fact, nearly half the commercial businesses use residential
size water heaters.
a lifecycle basis, gas-fired storage water heaters are typically
the least expensive means of heating water. One reason is
that per Btu, natural gas, as a primary energy source, is
usually much less expensive than electricity. Natural gas
water heaters typically provide hot water at costs less than
one-half that of electric water heaters. Also, mass production
of storage water heaters of 100-gallons or less make them
less costly to manufacture than other types of water heaters.
key differences between residential and commercial models
are that commercial units have slightly larger volumes and
much higher heat input rates than residential water heaters.
Commercial water heaters have higher setpoint temperatures
of 180oF compared to 140°F for residential water heaters.
They also have larger pipe connections, more rugged controls
and a few features only rarely found in residential models,
such as electric flue dampers and electronic ignition.
Gas Water Heater
Electric Water Heater
Water Heaters for Large Volume Users
Commercial applications may use two or more water
heaters manifolded together (not all brands/models can adapt
to this configuration). Parallel manifolding allows one or
more of the water heaters to be shut down while the others
operate; this gives uninterrupted hot water when a water heater
needs service or replacement. For a facility that has widely
varying levels of use, for example a stadium, such a system
allows most of the water heating capacity to be shut off during
periods when it won't be needed. Series manifolding, usually
two tanks in series, is often used for facilities that need
hot water at two different temperatures, for example, kitchens
and laundries. The first tank provides hot water at about
120°F for general service, while the second tank heats
some of the 120°F water to 180°F for dishwashers or
high temperature washing machines.
Commercial businesses that pay large electric demand
charges or much lower rates during off-peak hours may use
an off-peak water heater. These water heaters have very large
tanks to store sufficient hot water for their on-peak downtime
as well as controls that allow the electric elements to operate
only during off-peak hours. Off-peak water heaters are usually
only cost effective in areas where a large discount is offered
for off-peak power.