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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
VALVE W[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
WATER SHUT-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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