Worcester 24ijunior Installation And Servicing Instructions page 39

Yes
Turn off boiler. Remove
inner casing cover and
check position of
primary sensor (on
No
heat exchanger in
front of overheat
thermostat).
Is it correctly fixed to
pipe?
Yes
Remove combustion
chamber cover.
No
Is the sense electrode
and lead in good
condition and is gap
correct?
Yes
Remove multiway
No
connector from board
position ST16.
Is there continuity
from pin 10 (white
wire) to flame sensor?
Yes
Check the flashing
No
fault signal occur at
the start of a demand.
Yes
Relace control board.
NOTE: It is not
possible to reliably
check the cross-light
performance of the
burner, or the
efficiency of the
gas/water heat
exchanger.
If there is still a
problem, investigate
flue problems or
replace burner or
injector or heat
exchanger.
Re-fix sensor to pipe.
Replace flame sensor
or wiring.
Check flashing occurs Check flashing occurs during
at the end of a
demand. Pump could be partially
Gas valve leak is
detected. Clean pump & flush system.
39
a demand.
blocked.