Thermal Expansion; Water Supply Connections - Rheem GG50T06PVT Use And Care Manual

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.
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.
Vacuum Relief Valve
(Not Supplied)
If required, install per local codes
and valve manufacturer's
instructions.

Thermal Expansion

Determine if a check valve exists in the
inlet water line. Check with your local
water utility. 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

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
Heat trap
6" minimum
Hot water outlet to
fixtures
Water Heater Jacket
Temperature and pressure
relief valve
Manual gas shut-off
To gas supply
Ground joint union
Sediment trap
Cap
Thermostatic gas valve
Jacket door
Flammable Vapor Sensor
Auxiliary catch pan
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.
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.
Vent connector
1/4" per foot maximum slope up or
Union down for horizontal venting.
Shut-off
valve
Thermal expansion
tank (if required)
Drain
valve
Drain Pan Pipe to
suitable drain.
Anode
Blower assembly
Union
Heat trap
6" minimum
To cold water
supply
Shut-off valve
Relief valve discharge line
to suitable open drain.
Combustion Air
Inlet Openings
6" Air gap
9