Troubleshooting - A.O. Smith GPS-75 Instruction Manual

Please check guidelines below. For your safety, water heater service should be performed only by a qualified service technician.
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Read the GENERAL SAFETY INFORMATION section first.
INTELLI-VENT TROUBLESHOOTING CHART - RESIDENTIAL CONTROL
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Inadequate or no earth ground
sensed by the Intelli-Vent™
control.
Power supply to Intelli-Vent™
control has reversed polarity.
See training document ahstb02807
Pressure switch circuit remaining
closed for more than 5 seconds
after heating cycle begins.
Blower does not start.
service note:
Disconnect power - disconnect one
wire from the air pressure switch
or the vent temperature limit
switch. Turn power back on -
blower should start.
Pressure switch circuit remains open
longer than 5 seconds after the blower
is energized.
Blower may run continuously in
this condition.
service note:
To learn more about performing Air
Pressure Switch tests visit our web
site www.hotwater.com to download
technical bulletin A-023-06 Air Pressure
Switches.
The Intelli-Vent™ control has detected
an open ignitor circuit.
service note:
The resistance (ohms) of a hot surface
ignitor will increase over time. If the
resistance at room temperature is near
18.8 ohms - consider replacing the ignitor
as a preventative measure.
1. Ensure the wall outlet is properly grounded.
2. Ensure all ground connections/wires on the
water heater are secure.
1. Ensure the wall outlet is properly wired.
2. Ensure all internal 120 VAC wiring connections and
wiring harness have no reversed wires. 120 VAC
"hot" wire must connect to the on/off switch.
3. See training document ahstb02807.
1. Ensure air pressure switch circuit wiring is correct
and the air pressure switch is not jumpered.
2. Secure power to water heater, check continuity of air
pressure switch contacts with wires disconnected.
A If pressure switch contacts show continuity (closed
circuit) replace the pressure switch.
B If pressure switch contacts are open and all wiring
is correct - turn the power off for 10-20 seconds
then on again to clear the error code - if the error
code persists replace the Intelli-Vent™ control.
1. Ensure the blower is running - check for 120 VAC to
the blower when the heating cycle begins, check the
wiring. If the control does not energize the blower -
replace the Intelli-Vent™ control. If the blower fails to
start when energized - replace the blower assembly.
2. Ensure the air pressure switch sensing tube is properly
connected - not kinked or damaged.
3. Check continuity of vent temperature limit switch -
switch if contacts remain open under 160ºF (71°C).
4. Ensure the correct size of vent pipe (2", 3", 4") was used
per installation manual for vent length. Ensure maximum
number of elbows or equivalent feet of vent pipe has not
exceeded maximum limits.
5. Ensure there are no obstructions in the vent pipe.
6. Check air pressure switch performance - check pressure
with a digital manometer - check continuity of contacts.
(see service note in left column) If the switch proves
defective - replace the air pressure switch and or the
blower assembly as required.
7. If air pressure switch performance test results prove
the air pressure switch is working properly and error
code 4 persists - replace the Intelli-Vent™ control.
1. Check wiring to the hot surface ignitor - replace ignitor
assembly if wiring is damaged or worn.
2. Check ignitor assembly plug and the socket on the
Intelli-Vent™ body for good connection. Replace
ignitor assembly and/or control if necessary.
3. Check resistance of ignitor at room temperature 77ºF
(25°C) at the plug end. Replace ignitor if resistance
is not within 11.5 and 18.8 ohms at room temperature.
4. If results from the above tests were good and error
code 5 persists - replace the Intelli-Vent™ control.
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