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Start Uj_ Conditions
Thermal Expansion
Property Damage Hazard
+Avoid water heater damage.
- Install thermal expansion tank or device if necessary.
• Contact qualified installer or service agency.
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 relief 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 27.
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.
WATER HEATER (3)
HOT COLD / COLDWATER PRESSURE
r=====_-m _ _ iNLET FiTTiNG REDUCING
I (z)
PRESSURE GAUGE
WATER SHUT-OFF
=RECOMMENDED iNSTALLATiON
_VERTICAL MOUNTING)
WATER HEATER
COLD WATER
iNLET FiTTiNG FLOOR, CEILING JOIST, ETC.
\
OT COLD _ STRAPPING
EXPANSION d/
/ t
I PRESSURE GAUGE iNLET COLD
WATER SHUT-OFF
ALTERNATE RECOMMENDED INSTALLATION
-- -- (HORIZONTAL MOUNTING)
Thermal Expansion Tank Specifications
Mode!
Number
153.331020
153.331050
Tank
Capacity
In Gallons
2
5
Dimensions Pipe
in Inches Fitting
Diameter Lentth On Tank
8 (203 mm) 12-3/4 (323 mm) 3/4" Male
11(279 mm) 14-3/4 (375 mm) 3/4" Male
FIGURE 27.
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.
Expansion Tank Sizing Chart
Water Heater Capacity (Gallons
Inlet*
Water
Pressure
40psi
50psi
60psi
70psi
80psi
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
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.
*Highest recorded inlet water pressure in a 24 hour period or
regulated water pressure.
23
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