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START UP CONDITIONS
Thermal Expansion
Water supply system may, because of such events as high line
pressure, frequent cut-offs, and the effects of water hammer have
installed devices such as pressure reducing valves, check valves,
back flow preventers, etc., to control these types of problems.
When these devices are not equipped with an internal by-pass,
and no other measures are taken, the devices cause the water
system to be closed. As water is heated, it expands (thermal
expansion) and closed systems do not allow for the expansion
of heated water.
The water within the water heater tank expands as it is heated
and increases the pressure of the water system. If the relieving
point of water heater's temperature-pressure relief valve is
reached, the valve will relieve the excess pressure. The
temperature-pressure relief valve is not intended for the
constant relief of thermal expansion. This is an unacceptable
condition and must be corrected.
It is recommended that any devices installed which could create
a closed system have a by-pass and/or the system have an
expansion tank or device to relieve the pressure built by 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, see Figure
26 and Figure 26 A.
FIGURE 26.
TROUBlESHOOTING GUIDE
25
FIGURE 26A.
Thermal Expansion Tank Specifications
Tank
Model
Capacity
Number
In Gallons
Diameter
153.331051
5
11 (279 mm)
noTE: Expansion tanks are pre-charged with a 40 psi air
charge. If the inlet water pressure is higher than 40 psi, the
expansion tank's air pressure must be adjusted to match
that pressure, but must not be higher than 80 psi.
Strange Sounds
Possible noises due to expansion and contraction of some metal
parts during periods of heat-up and cool-down do not represent
harmful or dangerous conditions.
Condensation causes sizzling and popping within the burner area
during heating and cooling periods and should be considered
normal. See Condensation section.
Draft Hood Operation
Check draft hood operation by performing a worst case
depressurization of the building. With all doors and windows
closed, and with all air handling equipment and exhaust fans
operating such as furnaces, clothes dryers, range hoods and
bathroom fans, a match flame should still be drawn into the draft
hood of the water heater with its burner firing. If the flame is not
drawn toward the draft hood, shut off water heater and make
necessary air supply changes to correct.
Condensation
Whenever the water heater is filled with cold water, some
condensate will form while the burner is on. A water heater may
appear to be leaking when in fact the water is condensation.
This usually happens when:
• A new water heater is filled with cold water for the first time.
Dimensions
Pipe
in Inches
Fitting
length
On Tank
14-3/4 (375 mm)
3/4" Male
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