Service Procedure Vi: Flame Sensor Testing And Replacement - Bradford White UCG100H3993N Service Manual

Flame Sensor Testing and Replacement
Flame Sensor Testing Procedure
Refer to illustration below,
is there a minimum of 1 μA
during 1.5 second flame
proving period?
N
With flame sensor
disconnected from ignition
module, check continuity to
ground. Is there continuity
to ground?
N
Remove flame sensor from
water heater. Check
continuity from tip of flame
sensor to end of wire lead.
Is there continuity?
Y
Is flame sensor free of
oxidation?
N
Clean or replace flame
sensor. (See "Flame Sensor
Replacement Procedure".)
30
Service Procedure VI:
Y
Refer to ignition
module/control board
illustraion. (24 volts should
maintain beyond the 1.5
second flame proving period.)
Is there 24 VAC across brown
and blue wires coming out of
the control harness?
Y
Replace flame
sensor with
gasket and/or
wire lead. (See
"Flame Sensor
N
Replacement
Procedure").
Call for technical support.
N
Y
Is ceramic of flame
sensor cracked?
Y
Replace flame sensor.
(See "Flame Sensor
Replacement
Procedure".)
120 volt potential exposure. Use caution making voltage
checks to avoid personal injury. Flame sensor may be
too hot to handle, take necessary precautions.
Y
Flame sensing circuit O.K.
N
30
WARNING