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Start Up Conditions
Thermal Expansion
Property
Damage
Hazard
- Avoid water
heater damage.
o Install thermal
expansion
tank or device
if necessary,
• Contact
qualified
installer
or service
agency.
NOTE:
Expansion
tanks
are preocharged
with
a 40 psi air
charge,
mfthe intact 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 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
26.
Therma! Expansion
Tank Specifications
Tank
Dimensions
Mode_
Capacity
in Inches
Number
iln Gallons
Diameter
Length
153.331020
2
8 (203 ram)
12-3/4 (323 mm)
153.331050
5
11 (279 mm) 14-3/4 (375 mm)
Pipe
Fitting
On Tank
3/4" Mate
3/4" Mate
Expansion
Tank Sizing Chart
Water
Heater
Capacity
(Gallons)
h[et*
Water
Pressure
40psi
50psi
60psi
70psi
80psi
30
40
50
66
80
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
WATER
HEATER
(3)
(VERTICAL
MOUNTING)
WATER
HEATER
COLD
WATER
INLET
HTTING
HOT
COLD
FLOOR,
CEILING
JOBST,
ETC,
(3)
PRESSURE
REDUCING
VALVE WITH
(1_
BY-PASS
EXPANSION
J
TANK
:_
t
INLETCOLD
WATER SHUT=OFF
ALTERNATE
RECOMMENDED
INSTALLATION
(HORIZONTAL
MOUNTING)
F_GURE2&
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.
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
*Highest
recorded
inlet water
pressure
in a 24 hour period
or
regulated
water
pressure.
23
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