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15
If this water heater is installed in a closed water supply
system, such as one having a back-flow preventer in
the cold water supply line, means shall be provided to
control thermal expansion. Contact the water supplier
or local plumbing inspector on how to control this situ-
ation.
When this water heater system is supplying general
purpose hot water requirements for use by individuals,
a thermostatically controlled mixing valve is recom-
mended to reduce the risk of scald injury. Contact a
licensed plumber or the local plumbing authority for
further information.
Thermometer(s) should be installed so that they indi-
cate the water temperature at or near the outlet of the
storage tank.
Relief Valve
A new combination temperature and pressure (T & P)
relief valve, complying with the Standard for Relief
Valves and Automatic Gas Shut Off Devices for Hot
Water Supply Systems, ANSI Z21.22, must be
installed in the opening provided on top of the storage
tank, at the time of installation. No valve is to be placed
between the relief valve and the storage tank.
The pressure rating of the relief valve must not exceed
the 160 maximum working pressure indicated on the
water heater rating plate. The BTUH rating of the relief
valve must not be less than the BTUH input of the
heater.
Connect the outlet of the relief valve to a suitable open
drain. The discharge line must pitch downward from
the valve to allow complete draining (by gravity) of the
relief valve and discharge line. The discharge line
should be no smaller than the outlet of 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. Local codes
shall govern installation of relief valve.
FLOW SWITCH
INLET/OUTLET
WATER
CONNECTIONS
PRV
RATING PLATE
ON/OFF
SWITCH
ELECTRICAL
CONTROLS
LOCATION
HIGH LIMITS
PILOT LOCATION
COMBINATION
GAS VALVE
OPTIONAL
PUMP
Fig. 14: 0261 Low NOx WH1 with Pressure Relief Valve