Bradford White D Series Service Manual page 29

DANGER
120 volt exposure. To avoid personal injury,
use caution while performing this procedure.
Condition:
Pilot lights, no or low flame signal. Control
Display shows "4" or "62" for Error Codes
(Service Needed). Control continues to spark
until system "Lock Out".
Main burner will not light.
Check for loose or damaged flame sense
lead from pilot to Control Board. (see
illustration to the right). Is flame sense lead
okay?
Y
Check for loose or damaged ground wire(s)
from gas valve to control board. Check
continuity of wires with ohmeter. Are ground
wires okay?
Y
Check venting conditions or negative
pressure.
Is vent system okay?
Y
Is heater condensing causing pilot
interruption?
N
The microamp output of the pilot may be
checked by entering "Service Mode" on the
water heater display and pressing "Select"
until the flame current is shown. The control
must be in the heating mode with the pilot lit
to display a reading. See section on
accessing service mode on the water heater
display.
Micro-amp readings
0.000 Micro Amp = Replace control board or pilot if wire is
damaged.
1.0 micro amp or less = Clean pilot flame rod or replace pilot.
Be Careful When Making Voltage
Measurements or Jumping Terminals
Not to Damage or Deform Connectors or
Repair wire lead
N
or replace pilot.
Repair ground
N
wire(s) or replace
as needed.
Correct improper
venting condition.
N
Refer to Installation
Instructions
Make sure pilot shield is in place
and not bent or damaged (refer
to section on main burner and
pilot assembly) . Determine
Y
cause for condensing and
correct.
(Possible under sized water
heater or high demand periods.)
NOTE:
Check continuity of sense lead
to flame rod. If no continuity,
clean pilot flame rod or replace
pilot. Check pilot flame
appearance - if weak check for
clogged pilot orifice, bent pilot
tubing, or low inlet gas
pressure.
(see above illustration)
Page 29
SERVICE PROCEDURE D24-II
Pilot Operation Testing
CAUTION
Connector Pins.
Meter
Probe
Multi-meter set
to check
continuity.
Meter
Probe
Checking pilot flame sensor wire and flame
rod for continuity.
Heating
Status Operational
SELECT
Pilot flame sensor microamp output
shown in display using service mode.
Pilot must be lit to get reading.
Flame rod
A
Flame Current
SET
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