Temperature-Pressure Relief Valve - A.O. Smith POWER VENT GAS Installation And Operating Manual

TEMPERATURE-PRESSURE RELIEF VALVE

This heater is provided with a properly certifi ed combination
temperature - pressure relief valve by the manufacturer.
The valve is certifi ed by a nationally recognized testing
laboratory that maintains periodic inspection of production
of listed equipment of materials as meeting the requirements
for Relief Valves for Hot Water Supply Systems, ANSI
Z21.22 • CSA 4.4, and the code requirements of ASME.
If replaced, the valve must meet the requirements of local
codes, but not less than a combination temperature and
pressure relief valve certifi ed as indicated in the above
paragraph.
The valve must be marked with a maximum set pressure
not to exceed the marked hydrostatic working pressure of
the water heater (150 psi = 1,035 kPa) and a discharge
capacity not less than the water heater Btu/hr input rate
as shown on the water heater's rating plate.
For safe operation of the water heater, the relief valve
must not be removed from its designated opening nor
plugged.
The temperature-pressure relief valve must be installed
directly into the fi tting of the water heater designed for
the relief valve. Must terminate a maximum of 300mm
(12 in.) above a fl oor drain or external to the building. In
cold climates, it is recommended that the discharge pipe
be terminated at an adequate drain inside the building. Be
certain that no contact is made with any live electrical part.
The discharge opening must not be blocked or reduced
in size under any circumstances. Excessive length, over
9.1 m (30 ft.), or use of more than four elbows can cause
restriction and reduce the discharge capacity of the valve
(see Figures 3 & 19).
No valve or other obstruction is to be placed between the
relief valve and the tank. Do not connect tubing directly to
discharge drain unless a 300mm (12 in.) (Max.) air gap is
provided. To prevent bodily injury, hazard to life, or property
damage, the relief valve must be allowed to discharge
water in quantities should circumstances demand. If the
discharge pipe is not connected to a drain or other suitable
means, the water fl ow may cause property damage.
16
The Discharge Pipe:
• Shall not be smaller in size than the outlet pipe size
of the valve, or have any reducing couplings or other
restrictions.
• Shall not be plugged or blocked.
• Shall be of material listed for hot water distribution.
• Shall be installed so as to allow complete drainage of
both the temperature-pressure relief valve, and the
discharge pipe.
• Shall terminate a maximum of 300mm (12 in.) above a
fl oor drain or external to the building. In cold climates, it
is recommended that the discharge line be terminated
at an adequate drain inside the building.
• Shall not have any valve between the relief valve and
tank.
The temperature-pressure relief valve must be manually
operated at least once a year, (see Figure 17). Caution
should be taken to ensure that (1) no one is in front of or
around the outlet of the temperature-pressure relief valve
discharge line, and (2) the water manually discharged will
not cause any bodily injury or property damage because
the water may be extremely hot.
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FIGURE 17
316888-001 Rev. 00 dRaFt Jun 28 245