Temperature-Pressure Relief Valve; Water Line Connections; Closed Water Systems - A.O. Smith 100 Series Instruction Manual

TEMPERATURE-PRESSURE RELIEF VALVE

This water heater is provided with a properly rated/sized and certified
combination temperature - pressure relief valve by the manufacturer.
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 new valve must meet the requirements of Local/
National codes, but not less than a combination temperature and
pressure relief valve rated/sized and certified as indicated in the
above paragraph. The new 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 or kW input rate as shown on
the water heater's model rating plate.
For safe operation of the water heater, the temperature and pressure
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. To prevent leakage use pipe dope or Teflon tape on threads.
Install discharge piping 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.
No valve or other obstruction is to be placed between the relief valve
and the tank. Do not connect discharge piping directly to the 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 adequate 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.
Explosion Hazard
Temperature-Pressure Relief Valve
must comply with ANSI Z21.22-
CSA 4.4 and ASME code.
Properly sized temperature-
pressure relief valve must be
installed in opening provided.
Can result in overheating and
excessive tank pressure.
Can cause serious injury or death.
Property Damage Hazard
● The temperature-pressure relief-valve discharge pipe
must terminate at an adequate drain.
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 be in a continuously downward
direction 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 or other obstruction between the
relief valve and the drain. Water may drip from the discharge
pipe of the pressure-relief device and that this pipe must be
left open to the atmosphere
• Discharge must be in a frost free environment
The temperature-pressure relief valve must be manually operated
at least once a year, by a qualified service agent, to remove lime
deposits and to verify that it is not blocked; 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 in this manual, and replace
the temperature-pressure relief valve with a properly rated/sized
new one.
If you do not understand these instructions or have any questions
regarding the temperature-pressure relief valve call the toll free
number listed on back cover of this manual for technical assistance.

WATER LINE CONNECTIONS

This manual provides detailed piping installation diagrams. See Piping
Diagrams (page 43) for typical methods of application. Permanently
connect to the water mains and do not connect by use of a hose-
set. For the heater inlet and outlet connections, dielectric unions
are recommended. The water heater may be installed by itself, or
with a separate storage tank, on both single and two-temperature
systems. When used with a separate storage tank, the circulation
may be either by gravity or by means of a circulating pump. When
a circulating pump is used it is important to note that the flow rate
should be slow so that there will be a minimum of turbulence inside
the heater.

CLOSED WATER SYSTEMS

Water supply systems may, because of local/national code
requirements or such conditions as high line pressure, among others,
have installed devices such as pressure reducing valves, check
valves, and back flow preventers. Devices such as these cause the
water system to be a closed system.
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