Service Procedure Vii: Flame Sensor Testing And Replacement - Bradford White EF120T4003N3 Service Manual

Flame Sensor Testing and Replacement
Flame Sensor Testing Procedure
Refer to image below. Is
there a minimum of 1 μA
during 2 second flame
proving period? (may be
checked on digital display).
N
With flame sensor
disconnected from ignition
control board, 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, pg 36).
Service Procedure VII:
Y Y
Refer to ignition control board
illustration. (24-28 volts should
maintain beyond the 2 second
flame proving period.) Is there
24-28 VAC across brown and
blue wires (gas valve) coming
out of the control board
harness?
Y Y
Replace flame
sensor with gasket
and/or wire lead
(see Flame
Sensor
N
Replacement
Procedure, pg 36).
Y Y
Is ceramic of flame
sensor cracked?
Y
Replace flame sensor
(see Flame Sensor
Replacement
Procedure, pg 36).
WARNING
120 volt potential exposure. Use caution making
voltage checks to avoid personal injury. Flame
sensor may be HOT, take necessary precautions.
Y Y
Flame sensing circuit O.K.
N
Call Technical Support.
Call
N
Technical
Support.
120 Control Board Schematic
35
35