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Start Up 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 systems may, because of such events as high line
pressure, frequent cut-offs, the effects of water hammer among
others, 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 the 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 to relieve the pressure built by thermal expansion
in the water system. 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.
Thermal Expansion Tank Specifications
WATER HEATER
F_H_ #LD_ COLD WATER
iNLET FITTING
(3)
PRESSURE
REDUCING
VALVEW[TH
BY-PASS
PRESSURE GAUGE iNLET COLD
WATER SHUT-OFF
,=.===RECOMMENDED iNSTALLATiON
(VERTICAL MOUNTING)
WATER HEATER
COLD WATER
iNLET FITTING
\
k
HOT \COLD
FLOOR, CEILING JOIST, ETC.
]Lll
_ STRAPPING (3)
PRESSURE
REDUCING
VALVEWiTH
(1) BY-PASS
EXPANSION _/"
TANK :[__
PRESSURE GAUGE INLET COLD
WATERSHUT-OFF
ALTERNATE RECOMMENDED iNSTALLATiON
-- (HORIZONTAL MOUNTING)
FIGURE 43.
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.
Tank Dimensions Pipe
Model Capacity in inches Fitting
Number In Gallons Diameter Len,qth On Tank
153.331020 2 8(203mm) 12-3/4(323mm) 3/4"Male
153.331050 5 11(279 mm) 14-3/4 (375 mm) 3/4" Male
Expansion Tank Sizing Chart
Expansion
Tank
Capacity
Needed
Inlet*
Water
Pressure
40psi
50psi
60psi
70psi
8Ops!
Water Heater Capacity (Gallons)
30 40 50 66 80
2 2 2 5 5
2 2 2 5 5
2 2 5 5 5
2 2 5 5 5
2 5 5 5 5
*Highest recorded inlet water pressure in a 24 hour period or
regulated water pressure.
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.
Operational Conditions
SMELLY WATER
In each glass-lined water heater there is installed one anode
rod (see parts section) for corrosion protection of the tank.
Certain water conditions will cause a reaction between this rod
and the water. The most common complaint associated with the
anode rod is one of a "rotten egg smell". This odor is derived
from hydrogen sulfide gas dissolved in the water. The smell is
the result of four factors which must all be present for the odor
to develop:
A. A concentration of sulfate in the supply water.
B. Little or no dissolved oxygen in the water.
C. A sulfate reducing bacteria within the water heater. (This
harmless bacteria is non-toxic to humans.)
D. An excess of active hydrogen in the tank. This is caused by
corrosion protective action of the anode.
23
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