A.O. Smith ATI-140H-N Service Handbook page 32

into the slots, star ng at the
back and moving forward.
Make sure that no contact
is made with the gasket;
protect it from direct water
pressure. Rinse thoroughly.
6.4 Clear excessive water from the
burner with compressed air.
6.5 Inspect the gasket. Minor
surface tears are acceptable.
If the gasket shows major
separa ons, replace the
gasket before the unit is
returned to service.
7. Clean the fan:
7.1 Disconnect and remove the
fan from the combus on
chamber as follows:
7.1.1 Remove the clear air tube from
the bo om of the combus on
chamber. If needed, refer to
Figure 33, page 41.
7.1.2 Remove the 2 Phillips/hex
head screws poin ng down
from the fan using an 8"
long, #2 Phillips head screw
driver. There are 2 holes
in the case directly below
the screws to put the screw
driver through.
32 • Condensing Models: On-Demand Water Heater Service Handbook
7.1.3 Slide the fan toward you
to remove it from the rear
slots that hold it in place.
Remove the fan.
7.2 Blow compressed air into
the fan. The fan will rotate
and dust will fl y out of the
fan housing.
NOTE: You will reassemble
these items in reverse order
at the end of this procedure.
8. Clean the heat exchanger:
8.1 If you have a DV model,
remove the exhaust ven ng
from the top of the unit.
8.2 Place towels as follows:
•
Place one towel at
the bottom of the
combustion chamber
so that it covers the fan
discharge opening (fan
port).
•
Drape a second towel
so that it covers the
square opening of the
combustion chamber
(to prevent the entry of
airborne debris)
8.3 Use the air compressor to
blow air down through the
top of the heat exchanger
and through the vent collar.
At the same me
vacuum the dirt from the
combus on chamber.
Con nue un l all dirt has
been removed.
8.4 Inspect the heat exchanger.
If there is a white, solid,
crusty buildup in the heat
exchanger, please contact
technical service for
instruc on.
NOTICE: During the next
step, be gentle with the
sensor rods when cleaning
them. They will bend out of
place easily. If they are bent
out of place, the opera on
of the water heater could be
aff ected.
9. Clean the fl ame sensor and air/
fuel ra o rod (AFR) with sand
paper or other appropriate
abrasive, bringing it to a bright
fi nish.
Con nued...