Water Line Connections; Closed Water Systems; Thermal Expansion - State Water Heaters 100 Series Instruction Manual

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.
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 back
section of this manual) 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, di-electric 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.

therMal expansIon

As water is heated, it expands (thermal expansion). In a closed system
the volume of water will grow when it is heated. As the volume of water
grows there will be a corresponding increase in water pressure due
to thermal expansion. Thermal expansion can cause premature tank
failure (leakage). This type of failure is not covered under the limited
warranty. Thermal expansion can also cause intermittent temperature-
pressure relief valve operation: water discharged from the valve due
to excessive pressure build up. This condition is not covered under
the limited warranty. The temperature-pressure relief valve is not
intended for the constant relief of thermal expansion.
A properly sized thermal expansion tank should be installed on all closed
systems to control the harmful effects of thermal expansion. Contact a
local plumbing service agency to have a thermal expansion tank installed.
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