Worcester 24SiII Installation And Servicing Instructions page 37

No
Is the gas supply
connected and at the
correct pressure?
Yes
Remove front panel.
No
Reset and restart the
boiler. Can a flame be
seen through the spy
glass?
Yes
No
Is the boiler fully
water pressurised and
is all air vented?
Yes
No
Reset and restart the
boiler in CH mode.
Does the pump run?
Yes
Rectify gas supply
problem.
Remove inner cover.
No
Reset and restart the
boiler. Does a spark
occur across the
electrodes?
Yes
Turn off boiler. Remove
the multiway
connector from board
No
position ST16.
Test resistance across
connector contact
pins 1 and 2
(green wires)
and 8 and 9
(brown wires).
Are both reading
below 100 ohms?
Yes
Is there continuity
No
between pins 6 and 7?
(green wires to HL
stat)
Yes
Replace control board.
If problem not solved
replace gas valve.
Rectify fault.
Replace or repair
pump.
37
No
Are the electrodes and
gap and connections
in good order?
Yes
No
Test resistance of each
ignition cable.
Is it 2000-3000 ohms?
Yes
Replace
control board.
Remove both
connectors from gas
No
valve.
Is there continuity
from these
to multiway
connector?
Yes
Replace gas valve.
Replace overheat stat
or wiring to it.
Repair or replace
spark electrode
or HT leads
Replace (both) ignition
cables
Repair or replace
harness.