Rheem RTG-3 Series Use And Care Manual page 38

INSTALLATION INSTRUCTIONS
Water Supply
Relief Valve
A new pressure-relief valve, complying with the
Standard for Relief Valves and Automatic Gas
Shut-Off Devices for Hot Water Supply Systems,
ANSI Z21.22/CSA 4.4, must be installed at the
HOT water outlet connection of the water heater
during installation. Local codes shall govern the
installation of any relief valves.
NOTICE:
• The following drawing illustrates a pressure-only relief
valve. If local codes require a combination temperature
and pressure-relief valve, you may need to install an
extension piece to ensure that the relief valve probe is
not directly in the flow path of the water.
• Local codes govern the installation of relief valves. If
local codes require that a temperature and pressure-
relief valve be installed, the manufacturer recommends
a type 40XL Watts temperature and pressure-relief
valve or equivalent model be used.
• Manual operation of relief valves should be performed
at least once a year.
• If the relief valve on the system discharges
periodically, a problem exists. Turn off the water
heater, unplug the unit, and call for service.
Union
Relief Valve
Service
Valve
Hot
Water
Supply
Outlet
One end of the relief valve discharge line connects
to the HOT water outlet pipe as shown above.
The other end of the pipe should be routed to a
suitable drain to eliminate potential water damage.
38
For safe operation of the water heater, be sure
that:
The pressure rating of the relief valve must not
exceed 150 psi (1,034 kPa) or the maximum
working pressure of the water heater. (See the
rating plate on the water heater.)
The BTUH rating of the relief valve must equal or
exceed the BTUH input of the water heater. (See
the rating plate on the water heater.)
No valve of any type should be installed between
the relief valve and the water heater.
Discharge from the relief valve should be piped to
a suitable drain. Piping used should be of a type
approved for the distribution of hot water.
HOT and COLD water lines should be insulated
up to the water heater. See "Water Supply
Installation".
The discharge line must be NO SMALLER than the
outlet of the relief valve. The drain line must pitch
downward to allow for complete drainage of the
line and the valve.
The end of the discharge line should not be
threaded or concealed and should be protected
from freezing. No valve of any type, restriction,
or reducer coupling should be installed in the
discharge line.
Service Valve
Union
Cold Water
Service Valve
Relief Valve
Discharge Line