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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.
As water is heated, it expands (thermal expansion).
In a closed
system, the volume of water wilt grow. As the volume of water
grows, there wilt be a corresponding
increase in water pressure
due to thermal
expansion.
Thermal
expansion
can cause
premature
tank failure (leakage).
This type of failure is not
covered under the limited warranty. Thermal expansion can also
cause intermittent temperature-pressure
relief valve operation:
water discharged
from the valve due to excessive
pressure
build up. The temperature-pressure
relief valve is not intended
for the constant relief of thermal expansion. This condition is not
covered under the limited warranty.
A properly sized thermal expansion
tank should be installed
on all closed systems to control the harmful effects of 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 37.
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.
MASSACHUSETTS:
INSTALL
A VACUUM
RELIEF
IN COLD
WATER
LINE PER SECTION
19 MGL 142.
HOT WATER
THERMAL
OUT
EXPANSION
TANK
l
COLD
WATER
SUPPLY
F JU°ES
PRESSURE
\
PRESSURE
GAUGE
\
REDUCING
I
\
VALVE
WITH
/
_
(SHUT-OFF
VALVE)
IN
FIGURE 37.
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.
Thermal Expansion Tank Specifications
Model
Number
153.331020
153.331050
Tank
Dimensions
Pipe
Capacity
in Inches
Fitting
In Gallons
Diameter
Len£1th
On Tank
2
8 (203 mm)
12-3/4 (323 mm) 3/4" Male
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
80psi
Water Heater Capacity (Gallons)
30
40
50
66
82
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.
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.
Condensation
35
Whenever
the water heater is filled with cold water, some
condensate will form while the burner is on. Awater heater may
appear to be leaking when in fact the water is condensation.
This usually happens when:
•
A new water heater is filled with cold water for the first
time.
•
Burning
gas
produces
water
vapor
in water
heaters,
particularly high efficiency models where flue temperatures
are lower.
•
Large amounts of hot water are used in a short time and the
refill water in the tank is very cold.
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