15
4. BLOCKED EXHAUST
ADVANCED
BACK
locked
xhaust
0 days 0 hrs 0 mins ago
Error Code:
A8-1201
Restriction in exhaust pipe.
Check exhaust pipe and
termination for blockage.
Press the Advanced button for
CAUSES:
• The Blocked Exhaust Switch has detected a possible
restriction in the exhaust pipe.
•
CHECK/ REPAIR:
• Check pipe for restriction or excessive equivalent length.
• See Instruction Manual for pipe size, length and maximum number of elbows.
• Check actual pipe pressure with a manometer during blower operation..
5. FLAME SENSOR ERROR
ADVANCEDBACK
Flame Sensor(error)
0 days 0 hrs 1 mins ago
Error Code:
A9-17B
Flame Sensor rod detected flame
when gas valve should be off.
Shut off gas until repaired.
Call a service professional:
CAUSES:
• The Flame Sensor has detected ame when the Gas
Control Valve is supposed to be off.
CHECK/ REPAIR:
• Look through sight glass. If ame is present, shut the main gas supply off. See Gas Control Valve section below to conrm proper
operation.
• If ame is not present, cycle the unit Off by turning the Enable/Disable switch to Disable, wait for 5 seconds, and cycle the unit On by
turning the Enable/Disable switch to Enable to see if the error clears.
FLAME SENSOR
Ignition of the Burner is controlled electronically. The principle of operation for electronic ignition relies on ame sensing current to prove
the fuel gas owing to the Burner has been ignited.
Flame sensing requires an adequate earth ground to the water heater’s Burner. See Electrical Connections – All Models (page 26).
FLAME SENSING OPERATION
• The Flame Sensor is a metal (conductor) rod mounted in a ceramic insulator.
• The Control System applies an AC voltage to the Flame Sensor through a single wire.
• The burner ame will conduct a small amount of electrical current.
• The burner must be properly grounded for current to ow from the Flame Sensor to the Burner.
• During ignition the burner ame must make complete and continuous contact with the Flame Sensor.
• As the AC current ows from the Flame Sensor through the burner ame to the (grounded) Burner the AC current is “rectied” and
becomes a DC current.