Kenmore Power Miser 12 153.320493 HT - Manual (Page 21)

Troubleshooting Guide
Start Up Conditions
THERMAL EXPANSION
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 (ther­
mal expansion) and closed systems do not allow for the expan­
sion 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 cor­
rected.
It is recommended that any devices installed which could create a
closed system have a by-pass and/or the system have an expan­
sion tank 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.
Thermal Expansion Tank Specifications
Model Tank Capacity Dimensions in Inches Pipe Fitting
Number In Gallons Diameter Length On Tank j
153.331020 2 8 inches 12/^ inches X' Male
153.331050 5 11 inches l4y< inches X' Male 1
Expansion Tank Sizing Chart
Inlet*
Water
Water Heater Capacity (Gallons)
Expansion
Tank
Pressure 30 40 50 66 82
40psi 2 2 2 5 5
Capacity 50psi 2 2 2 5 5
Needed 60psi 2 2 5 5 5
70psi 2 2 5 5 5
80psi 2 5 5 5 ....... 5......
*Highest recorded inlet water pressure in a 24 hour period or
regulated water pressure.
NOTE: Exp ansion 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 COLD WATERHWTER
, — C O L D WATER
^ > nlet fitting
(3)
PRESSURE
REDUCING
VALVE WITH
BY-PASS
(I)
EXFVLNSION
TANK
I
(2) ~y~ f
PRESSURE GAUGE '^LET COLD
WATER
SHUTOFF
RECOMMENDED INSTALLATION
(VERTICAL MOUNTING)
WATER HEATER
COLD WATER
INLET FITTING
FLOOR, CEIUNG
JOIST, ETC.
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.
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