Worcester 24ijunior

36
Is there a 230V AC live
supply across
Terminal ST2 pins L
and N?
Switch off electrical
power.
Has fuse F1 blown?
Replace fuse and
investigate cause.
Suggestions: Cable
damage, connections
to (or faults within)
pump, fan, external
230V controls,
transformer or board.
Check electrical
supply to boiler.
Has fuse F2 blown?
TEST A
No
Yes
Yes
No
Replace fuse.
This will be caused by
fuse fatigue or by the
board.
Remove control board from facia
and separate transformer from
board. Measure resistance across
the two pairs of adjacent pins on
the transformer. Is any coil above
100 ohms?
Replace transformer.
Yes
Yes
No
Replace
control
board.
No
NOTE: It is normal for
there to be no facia
lights if the boiler is in
normal overtempera-
ture condition.
Continue this test if
this fault occurs when
the appliance is cold.
Is there a 230V AC live
supply across
Terminal ST2 pins Lr
and N?
TEST B
No
Yes
Yes
Replace
control
board.
NOTE: Lights will be
off and pump will run
if boiler is in 3min
anticycle condition.
With CH control knob
fully clockwise, if
there is still no CH
function, continue:
There is no heat
demand. Check room
thermostat or external
programmer (or link).
Is there a facia
mounted programmer
at connection ST5 at
right-hand end of
board?
No
No
Remove programmer
connector from edge
of board. Does the
boiler now ignite?
Correctly set or
replace programmer.
Yes