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Typical Installation
Safety Instructions Installation Instructions Operating Instructions Care and Cleaning Troubleshooting Tips Customer Service
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 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 (see illustration below). 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.
Install a shut-off valve in the cold water line near the water heater. Dielectric unions are not required for
protection of the water heater. At the installer’s option, heat traps formed from piping as illustrated
below can be used to reduce heat loss from piping.
IMPORTANT: This water
heater is supplied with
inlet and outlet heat traps
to help conserve energy.
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 or
heat traps.
WARNING: The water heater should not be installed in a space where liquids which give off flammable vapors
are to be used or stored.
Union
Union
Blower Assembly
Vacuum Tubing
Electric Cord
Ground Joint
Union
Sediment Trap
3" Min.
Drain Valve
Thermostat
Heat Trap
6" Min.
Heat Trap
6" Min.
Shutoff
Valve
To Cold
Water
Supply
Temperature &
Pressure
Relief Valve
Manual Gas
Shutoff
To Gas Supply
Cap
Hot Water
Outlet
to Fixtures
Flue Pipe (ANSI / ASTM / CSA Approved
PVC, CPVC or ABS) Connected to
Outside Vent Terminal (See VENTING
Section for details.)
Relief Valve Discharge
Line to Suitable Open
Drain
Auxiliary
Catch Pan
Air Gap
6" min.
Suitable
Open Drain
Thermal Expansion
Tank (if required)
On/Off Switch
9
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