Unit installation

34
TROUBLESHOOTING
IGNITION MODULE SYSTEM
Before calling your service agent, the following checklist should
be examined to eliminate obvious problems from those requiring
replacement or servicing.
— Check that “main manual gas shutoff valve” is fully open and
that gas service has not been interrupted.
— Check that after following the appliance OPERATING
INSTRUCTIONS, the “Top Knob” of the appliance gas valve is
in “ON” position.
— Check electrical supply to the appliance for possible blown
(or tripped) fusing or power interruption.
— Is the water temperature in tank below the thermostat dial
setting on the appliance thermostat (calling for heat)?
— It is possible that the high limit (E.C.O.) has functioned to shut
off the appliance. See FEATURES — Water Temperature
Control for reset procedure. Contact your serviceman if limit
continues to function to shut off appliance.
TROUBLESHOOTING FLUE DAMPER DRIVE UNIT
FLUE DAMPER DRIVE UNIT NOT HAVING NORMAL/
SERVICE SWITCH
STEP 1: INSPECT DAMPER - Lower the thermostat so the unit
will not be calling for heat; then inspect the damper.
• If the damper is open, go to step 2.
• If the damper is closed, go to step 3.
STEP 2: CHECK THE DAMPER DRIVE PC BOARD - Check for
24 VAC between the black PC board wire and the white PC
board wire.
• If 24 VAC is not present, check the black wire connections
between the PC board and the high limit.
• If 24 VAC is present, go to step 3.
STEP 3: TESTING THE PC BOARD AND THE MOTOR - Check
for 24 VAC between the two motor lead connection terminals of
the PC board. The motor leads can be disconnected from the
terminals for this test.
• If 24 VAC is not present, replace the circuit board
assembly.
• If the 24 VAC is present, this verifies the motor is receiving
voltage but not running; replace motor.
FLUE DAMPER DRIVE HAVING A
NORMAL/SERVICE SWITCH
STEP 1: WITH THE SWITCH IN NORMAL POSITION SET THE
THERMOSTAT TO CALL FOR HOT WATER - Check for 24 VAC
between the PC board white and black wires.
• If 24 VAC is not present, check the wiring between the
black wire and ECO.
• If 24 VAC is present, go to Step 2.
STEP 2: WITH THE SWITCH IN NORMAL POSITION SET THE
THERMOSTAT TO CALL FOR HOT WATER - Check for 24 VAC
between the PC board yellow and white wires.
• If 24 VAC is present, go to Step 3.
• If 24 VAC is not present then check between yellow wire
and thermostat.
STEP 3: WITH THE SWITCH IN NORMAL POSITION SET THE
THERMOSTAT TO CALL FOR HOT WATER - Check for 24 VAC
between the PC board red and white wires.
• If 24 VAC is present then problem is not with damper drive;
check ignition module and gas valves.
• If 24 VAC is not present then go to Step 4.
STEP 4: WITH THE THERMOSTAT CALLING FOR HOT WATER,
PLACE THE SWITCH IN THE SERVICE POSITION AND VERIFY
THE DAMPER DISC IS VERTICAL - Check for 24 VAC between
the PC board red and white wires.
• If 24 VAC is present then problem is not with damper
drive; check ignition module and gas valves.
• If 24 VAC is not present then replace damper drive PC
board.
SERVICE
The installer may be able to observe and correct certain problems
which may arise when the unit is put into operation. HOWEVER,
it is recommended that only qualified servicemen, using
appropriate test equipment, be allowed to service the heater.
As preliminary step, check wiring against diagram, check for
grounded, broken or loose wires. Check all wire ends to be sure
that they are making good contact.
ELECTRICAL SERVICING
CAUTION
LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN
SERVICING CONTROLS. WIRING ERRORS CAN CAUSE
IMPROPER AND DANGEROUS OPERATION.
VERIFY PROPER OPERATION AFTER SERVICING.
REPLACEMENT PARTS
Replacement parts may be ordered through A.O. Smith dealers,
authorized servicers or distributors. Refer to the Yellow Pages for
where to call or contact the A.O. Smith Water Products Company,
Product Service Division, 5621 West 115th Street, Alsip, IL 60803,
1-800- 433-2545. For Canada contact: A.O. Smith Enterprises
Ltd., P.O. Box 310, 768 Erie Street, Stratford, Ontario, Canada
N5A 6T3, 519-271-5800. When ordering parts be sure to state
the quantity, part number and description of the item(s) including
the complete model and serial number as it appears on the
product. Refer to the parts list for more information.