American Water Heater DCG - Manual (Page 13)

13 13
Temperature and Pressure
Relief Valve
For protection against excessive pressures and
temperatures, a temperature and pressure relief valve
must be installed in the opening marked “T & P RELIEF
VALVE” (See Figure 9). This valve must be design
certified by a nationally recognized testing laboratory
that maintains periodic inspection of the production of
listed equipment or materials as meeting the
requirements for Relief Valves and Automatic Shut-off
Devices for Hot Water Supply Systems, ANSI Z21.22.
(CSA4.4, Temperature, Pressure, Temperature and
Pressure Relief Valves and Vacuum Relief Valves in
Canada). The function of the temperature and pressure
relief valve is to discharge water in large quantities in
the event of excessive temperature or pressure devel-
oping in the water heater. The valve's relief pressure
must not exceed the working pressure of the water
heater as stated on the data plate.
Important: Only a new temperature and pressure relief
valve should be used with this water heater. Do not use
an old or existing valve as it may be damaged or not
adequate for the working pressure of the new water
heater. Do not place any valve or piping between the
relief valve and the tank.
The Temperature & Pressure Relief Valve:
• Must not be in contact with any electrical part.
• Must be connected to an adequate discharge
line.
• Must not be rated higher than the working
pressure shown on the data plate of the water
heater.
• The BTUH rating of the T & P valve must be
greater than, or equal to, the input rating of the
water heater.
The Discharge Line:
• Must not be smaller than the pipe size of the
relief valve or have any reducing coupling
installed in the discharge line.
• Must not be capped, blocked, plugged or
contain any valve between the relief valve and
the end of the discharge line.
• Must terminate a maximum of 6 inches (152mm)
above a floor drain or external to the building.
• Must be capable of withstanding 250°F (121°C)
without distortion.
• Must be installed to allow complete drainage of
both the valve and discharge line.
Figure 9: T&P Relief Valve
Explosion Hazard
If the temperature and pressure relief
valve is dripping or leaking, have a
qualified service technician replace it.
• Do not plug valve.
• Do not remove valve.
Failure to follow these instructions can
result in death or explosion.
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