Temperature-Pressure Relief Valve - A.O. Smith RESIDENTIAL GAS WATER HEATER Instruction Manual

Figure 10 shows the typical attachment of the water piping to the
water heater. The water heater is equipped with 3/4 inch NPT
water connections.
NOTE: If using copper tubing, solder tubing to an adapter before
attaching the adapter to the water heater connections. Do not
solder the water lines directly to the water heater connections.
It will harm the dip tube and damage the tank.
T & P Valve and Pipe Insulation (if supplied)
Remove insulation for T & P valve and pipe connections from carton.
FIGURE 11.
Fit pipe insulation over the incoming cold water line and the hot water
line. Make sure that the insulation is against the top cover of the
heater.Fit T & P valve insulation over valve. Make sure that the
insulation does not interfere with the lever of the T & P valve.
Secure all insulation using tape.

TEMPERATURE-PRESSURE RELIEF VALVE

This heater is provided with a properly certified combination
temperature - pressure relief valve by the manufacturer.
The valve is certified by a nationally recognized testing laboratory
that maintains periodic inspection of production of listed equipment
of materials as meeting the requirements for Relief Valves and
Automatic Gas Shut-off Devices 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
certified 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 input rate as shown on the model 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 fitting of the water heater designed for the relief valve. Position
the valve downward and provide tubing so that any discharge will exit
only within 6 inches (15.2 cm) above, or at any distance below the
structural floor. 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 30 feet (9.14
m), or use of more than four elbows can cause restriction and reduce
the discharge capacity of the valve, see Figures 10 or 14.
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 6" (15.2 cm) 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
flow may cause property damage.
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 at an adequate drain.
• 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. 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.
If after manually operating the valve, it fails to completely reset and
continues to release water, immediately close the cold water inlet to
the water heater, follow the draining instructions, and replace the
temperature-pressure relief valve with a new one.
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