Temperature-Pressure Relief Valve - A.O. Smith Commercial gas water heaters Instruction Manual

Figures 2 and 10 show 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 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 Btu/hr input rate as shown on the water heater's
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.
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.
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