A.O. Smith GDV, Instruction Manual

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The temperature-pressure relief valve must be installed directly
into the fi tting of the water heater designed for the relief valve.
Position the valve downward and provide tubing so that any dis-
charge will exit only within 6 in. above, or at any distance below
the structural fl oor. 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 ft., or use of more than four elbows can cause restriction
and reduce the discharge capacity of the valve, see Figures 4
or 9.
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 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 oth-
er suitable means, the water fl ow 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.
Must terminate a maximum of six inches above a fl oor drain
or external to the building. In cold climates, it is recommend-
ed that the discharge pipe 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 oper-
ated 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 re-
place the temperature-pressure relief valve with a new one.
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WATER (POTABLE) HEATING AND SPACE HEATING
All piping components connected to this unit for space heat-
ing applications shall be suitable for use with potable water.
Toxic chemicals, such as those used for boiler treatment,
shall NEVER be introduced into this system.
This unit may NEVER be connected to any existing heating
system or component(s) previously used with a non-potable
water heating appliance.
When the system requires water for space heating at tem-
peratures higher than required for domestic water purposes,
a mixing valve must be installed, see Figure 6 for suggested
piping arrangement.
FIGURE 6
CLOSED WATER SYSTEM
A closed system will exist if a back-fl ow preventer (check valve),
pressure reducing valve, or other similar device is installed in the
cold water line between the water heater and the street main (or
well). Excessive pressure may develop due to the thermal ex-
pansion of heated water causing premature tank failure or inter-
mittent relief valve operation. This type of failure is not covered
by the limited warranty. An expansion tank may be necessary
in the cold water supply to alleviate this situation, see Figure 1.
Contact the local plumbing authority.
If the temperature and pressure relief valve on the appliance
discharges periodically, this may be due to thermal expansion in
a closed water supply system. Contact the water supplier or local
plumbing inspector on how to correct this situation. DO NOT
PLUG THE TEMPERATURE AND PRESSURE RELIEF VALVE.
The water supply pressure should not exceed 80 psi. If this oc-
curs, a pressure reducing valve with a bypass should be installed
in the cold water inlet line. This should be placed on the supply
to the entire house in order to maintain equal hot and cold water
pressures.
1.
2.
3.
4.