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Thermal Expansion
Property Damage Hazard
• Avoid water heater damage.
• install thermal expansion tank or device if necessary.
• Contact qualified installer or service agency.
As water is heated, it expands (thermal expansion). In a closed
system, the volume of water wilt grow. As the volume of water
grows, there wilt 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. See
Figure 42.
TABLE 5
Thermal Expansion Tank Specifications
Model
Number
153.331020
153.331050
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.
HOT
I I
WATER HEATER
COLD WATER
INLET FITTING
HOT
WATER HEATER (3)
_L_ / COLD WATER PRESSURE
INLET FITTING REDUCING
VALVE WITH
BY-PASS
COLD
(2)
PRESSURE GAUGE INLET COLD
WATER SHUT-OFF
RECOMMENDED INSTALLATION
(VERTICAL MOUNTING)
FLOOR, CEILING JOIST, ETC,
(3)
PRESSURE
REDUCING
VALVE WITH
(1) BY-PASS
EXPANSION /
/ t
PRESSURE GAUGE-- INLET COLD
WATER SHUT-OFF
ALTERNATE RECOMMENDED INSTALLATION
(HORIZONTAL MOUNTING)
Tank Dimensions Pipe
Capacity in Inches Fitting FIGURE 42.
In Gallons Diameter Len£1th On Tank
2 8 (203 mm) 12-3/4 (323 mm) 3/4" Male
5 11 (279 mm) 14-3/4 (375 mm) 3/4" Male Strange Sounds
TABLE 6
Expansion Tank Sizing Chart
Inlet*
Water
Pressure
40psi
50psi
60psi
70psi
80psi
Water Heater Capacity (Gallons)
30 40 50 66 82
Expansion 2 2 2 5 5
Tank 2 2 2 5 5
Capacity 2 2 5 5 5
Needed 2 2 5 5 5
2 5 5 5 5
*Highest recorded inlet water pressure in a 24 hour period or regulated
water pressure.
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
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