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6
Installing the water heater
Thermal Expansion
Determine 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 “closed water system.”
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 “thermal
expansion.” 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 “closed water system,” however, prevents
the expanding water from flowing back into
the main supply line, and the result of “thermal
expansion” 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.
Water Supply Connections
Refer to the illustrations below and on the
next 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 if necessary. The HOT and COLD
water connections are clearly marked and
are 3/4" NPT on all models. Install a shut-off
valve in the cold water line near the water
heater. Local codes may require an anti-
siphon device on the water inlet of a side
connect water heater.
FRONT OF WATER HEATER
Anode Location
Cold Water
Inlet Coupling
Electrical
Junction
Bracket
Hot Water
Outlet Coupling
Temperature & Pressure
Relief Valve Coupling
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