49
INSTALLATION INSTRUCTIONS
Plumbing
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.
NOTICES:
• 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.
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.
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 page 50.
• 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.
Cold Water Supply
Shut-Off Valve
Union
Union
Service
Valve
Service
Valve
Relief
Valve
Cold Water
Supply Inlet
Hot Water
Supply Outlet
Relief Valve
Discharge Line
