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Closed System/Thermal Expansion
As water is heated, it expands (thermal expansion). In a closed
system, the volume of water will grow. 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. The
temperature-pressure relief valve is not intended for the constant
relief of thermal expansion. This condition is not covered under
the limited warranty.
A properly sized thermal expansion tank should be installed
on all closed systems to control the harmful effects of thermal
expansion. Thermal expansion tanks are available from Sears
stores and through the Sears Service Centers. Contact the
local plumbing inspector, water supplier and/or the Sears
Service Center for assistance in controlling these situations.
(For additional information, see the Troubleshooting Guide later
in this manual.)
Temperature and Pressure Relief Valve
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.
TEMPERATURE AND PRESSURE (T&P)
RELIEF VALVE (OPTIONAL TOP T&P
RELIEF VALVE NOT SHOWN)
DISCHARGE PIPE
(DO NOT CAP OR PLUG)
DRAIN LINE
3/4” ID
MINIMUM
1” MINIMUM
METAL
6” MAXIMUM
DRAIN PAN
AIR GAP
DRAIN
FIGURE 25.
For protection against excessive pressures and temperatures,
a temperature and pressure relief valve must be installed in the
opening marked “T & P RELIEF VALVE.” (See Figure 25). This
valve must be design certified by a nationally recognized testing
laboratory that maintains periodic inspection of the production
of listed equipment or materials as meeting the requirements
for Relief Valves for Hot Water Supply Systems, ANSI Z21.22.
The function of the temperature and pressure relief valve is to
discharge water in large quantities in the event of excessive
temperature or pressure developing in the water heater. The
valve’s relief pressure must not exceed the working pressure of
the water heater as stated on the rating plate.
IMPORTANT: Only a new temperature and pressure relief valve
should be used with your water heater. Do not use an old or
existing valve as it may be damaged or not adequate for the
working pressure of the new water heater. Do not place any
valve between the relief valve and the tank.
The Temperature & Pressure Relief Valve:
•
Must not be in contact with any electrical part.
•
Must be connected to an adequate discharge line.
•
Must not be rated higher than the working pressure shown
on the rating plate of the water heater.
The Discharge Line:
•
Must not be smaller than the pipe size of the relief valve or
have any reducing coupling installed in the discharge line.
•
Must not be capped, blocked, plugged or contain any valve
between the relief valve and the end of the discharge line.
•
Must terminate a maximum of six inches above a floor
drain or external to the building. In cold climates, it is
recommended that the discharge line be terminated at an
adequate drain inside the building.
•
Must be capable of withstanding 250°F (121°C) without distortion.
•
Must be installed to allow complete drainage of both the
valve and discharge line.
T&P Relief Valve and Pipe Insulation
1.
Locate the temperature and pressure relief valve on the water
heater (also known as a T&P relief valve). See Figure 26.
2.
Locate the slit running the length of the T&P relief valve
insulation.
3.
Spread the slit open and fit the insulation over the T&P relief
valve. See Figure 26. Apply gentle pressure to the insulation
to ensure that it is fully seated on the T&P Relief Valve. Once
seated, secure the insulation with duct tape, electrical tape,
or equivalent. IMPORTANT: The insulation and tape must not
block the discharge opening or hinder access to the manual
relief lever (Figure 26). Ensure a discharge pipe is installed
into the T&P valve discharge opening per the instructions in
this manual.
4.
Locate the hot water (outlet) & cold water (inlet) pipes to the
water heater.
5.
Locate the slit running the length of a section of pipe insulation.
6.
Spread the slit open and slip the insulation over the cold water
(inlet) pipe. Apply gentle pressure along the length of the
insulation to ensure that it is fully seated around the pipe. Also,
ensure that the base of the insulation is flush with the water
heater. Once seated, secure the insulation with duct tape,
electrical tape, or equivalent.
7.
Repeat steps 5 and 6 for the hot water (outlet) pipe.
8.
Add additional sections of pipe insulation as needed.
T&P RELIEF VALVE INSULATION
MANUAL RELIEF
LEVER
T&P RELIEF
VALVE
T&P RELIEF VALVE
DRAIN LINE
FIGURE 26.
Page 23
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