32
Remove front panel.
Reset and restart the
boiler. Can a flame be
seen through the spy
glass?
Turn off boiler. Remove
inner cover and
combustion chamber
cover. Is the sense
electrode and lead in
good condition and is
gap correct.
Remove multiway
connector from board
position ST16.
Is there continuity
from contact 11 (white
wire) to flame sensor?
Does the flashing fault
signal occur at the
start of a demand?
Replace control board (Section 15.4.12).
Note: It is not possible to reliably Check
the cross-light performance of the burner.
In the unlikely event of such a fault,
investigate flue problems or replace
burner or injector. (Section 15.4.4).
Flashing occurs at end
of demand. Replace
gas valve.
(Section 15.4.1).
Remove inner cover.
Reset and restart the
boiler. Does a spark
occur across the
electrodes?
Remove the 5 way
connector from the
gas valve and
measure the DC
voltage across the
violet and grey wires
and then brown and
yellow wires during
the spark period. Is
there 20-30V DC in
both cases?
Replace gas valve.
(Section 15.4.1 ).
Repair or replace flame
sensor
(Section 15.4.3)
or wiring.
Replace control board.
(Section 15.4.11 ).
Are the electrodes and
gap and connections
in good order?
Replace control board.
(Section 15.4.11).
Remove multiway
connector from
control board position
ST16. Is there
continuity of violet
and brown wires
between connectors
Repair or replace
harness.
Repair or replace
electrodes
(Section 15.4.2/3)
or HT leads
Is the gas supply
connected and at the
correct pressure?
Rectify gas supply
problem.
FAIL POINT H “Burner Lockout”
No
No No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
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