Installing the water heater.
Thermal ExpansionWater Supply ConnectionsDetermine if a check valve exists in the
inlet water line.It may have been installed in
the cold water line as a separate back flow
preventer, or it may be part of a pressure
reducing valve, water meter or water softener.
A check valve located in the cold water inlet
line can cause what is referred to as a
“cclloosseedd wwaatteerr ssyysstteemm.”A cold water inlet
line with no check valve or back flow prevention
device is referred to as an “open” water
system.
As water is heated, it expands in volume and
creates an increase in pressure within the
water system. This action is referred to as
“tthheerrmmaall eexxppaannssiioonn.” In an “open” water
system, expanding water which exceeds the
capacity of the water heater flows back into
the city main where the pressure is easily
dissipated.
A “cclloosseedd wwaatteerr ssyysstteemm,” however, prevents
the expanding water from flowing back into
the main supply line, and the result of
“tthheerrmmaall eexxppaannssiioonn”can create a rapid and
dangerous pressure increase in the water
heater and the system piping. This rapid
pressure increase can quickly reach the safety
setting of the relief valve, causing it to
operate during each heating cycle. Thermal
expansion, and the resulting rapid and
repeated expansion and contraction of
components in the water heater and piping
system can cause premature failure of the
relief valve, and possibly the heater itself.
Replacing the relief valve will not correct the
problem.
The suggested method of controlling thermal
expansion is to install an expansion tank in
the cold water line between the water heater
and the check valve. The expansion tank is
designed with an air cushion built in that
compresses as the system pressure
increases, thereby relieving the over pressure
condition and eliminating the repeated
operation of the relief valve. Other methods
of controlling thermal expansion are also
available. Contact your installing contractor,
water supplier, or plumbing inspector for
additional information regarding this subject.
NOTICE: Do not apply
heat to the HOT or COLD
water connections. If sweat
connections are used, sweat
tubing to adapter before fitting
adapter to the water
connections on heater. Any
heat applied to the water
supply fittings will permanently
damage the dip tube and/or
heat traps.
Customer Service Troubleshooting Tips Care and Cleaning Operating Instructions Installation Instructions Safety Instructions
6
Refer to the illustrations on the following
page for suggested typical installation.
The installation of unions or flexible copper
connectors is recommended on the hot
and cold water connections so that the
water heater may be easily disconnected
for servicing. Connect cold water supply
line to 3/4” pipe connection near bottom
of water heater on the 6 gallon and 20
gallon models. Install a shut-off valve and
a drain valve (not supplied with heater,
except 2 1/2 gal. models) in cold water line
near water heater. Connect hot water line
to 3/4” pipe connection marked HOT on
side near top of water heater. On the
2 1/2 gallon models, the hot and cold
water connections are 1/2” pipe
connections and are located on top of the
heater. Local codes may require an
anti-siphon device on the water inlet of a
side connect water heater.
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