Afr Rod - A.O. Smith 710 ASME Service Manual

10-6. AFR rod

Unit Part #
Function
Failure event
Effects on the water
heater if AFR rod fails
Error codes when the
AFR rod fails
Diagnostic
Color / Number of wires
The AFR rod is assembled with the flame rod.
Detecting elements (AFR and flame rods)
Leads to computer board
F l a m e r o d
#106
-Checks flame conditions during combustion.
-When AFR rod detects unexpected flame conditions, the the computer of
the water heater makes adjustments in the fan motor speed to compensate.
1. Unable to detect flames when flames actually do occur
2. Detecting a false flame when no flames actually occur
1. The water heater will not initiate the ignition process. The "721" error
code will display.
2. The fan motor speed cannot be modulated properly under abnormal flame
conditions, which can result in excessive CO emission.
101
1. Visual inspection: connection / braking of wires, soot on it.
2. Check voltages: proper range of values are shown below.
Yellow(8) - AFR rod
(Between the flame rod and
the computer board)
A F R R o d
AOS Part # 319143-035
391
3 / 4 " ( 1 7 .5 m m )
20
CONFIDENTIAL
710 / 710 ASME Service Manual
Checkpoint
991
(During operation)
More than DC 0.5 μA
Ver. 1.00
I