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Installing the water heater.
10
Thermal Expansion
Determine if a check valve exists in the
inlet water line. Check with your local
water utility company. 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 the 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 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.
Water Supply Connections
Refer to the illustration below 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.
IMPORTANT: 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 cold water
connections on heater.
Any heat applied to
the cold water supply
fittings will permanently
damage the dip tube
and/or heat traps.
To gas supply
Relief valve discharge line to suitable
drain
Manual gas shut-off
Sediment trap
Anode Rod (Located under top pan) Not accessible. Refer
to Protection Plus Kit for additional protection.
Temperature and
pressure relief valve
Flue baffle
(underneath)
Hot water outlet to fixtures
To cold water supply
Jacket door
Thermostat
Ground joint union or ANSI design certified
semi-rigid or flexible gas appliance connector
Piezo Igniter Striker
Drain valve
NOTICE: The National
Fuel Gas Code (NFGC)
mandates a manual
gas shut-off valve: See
(NFGC) for complete
instructions. Local
codes or plumbing
authority requirements
may vary from
the instructions or
diagrams provided and
take precedent over
these instructions.
Typical Installation
Vacuum Relief Valve
(Not Supplied)
If required, install per local codes
and valve manufacturer’s
instructions.
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