My Worcester Bosch 24CDi combi boiler keeps occasionally entering its
'burner lockout' state. The problem is so intermittent that resetting
the boiler always brings it back to life and I have so far been unable
to observe/determine whether the boiler is entering this state as a
result of it failing to ignite, partial ignition, igniting but failing
to detect the flame or the flame extinguishing when it shouldn't.
In the hope that it is either the spark electrodes or flame sensor
that are to blame (i.e. not a more complicated/expensive cause like
the control board, gas valve or gas supply etc) I purchased
replacements whilst it was convenient to obtain them (and negligible
Can anyone tell from the following photos whether it looks like the
spark electrodes and/or flame sensor are in need of replacement? I
appreciate it may be hard to tell given that most of the time the
boiler works fine and so if either is to blame it must be due to a
have verified the correct gaps (3-4mm spark electrodes and 5-6mm
flame sensor) and the boiler is at least 5 (possibly 7 or more) years
old now if that helps.
Unfortunately the replacement of the flame sensor requires the removal
of the burner, i.e. disconnection from the gas valve, and I didn't
feel competent that I could ensure (through testing) gas soundness of
the reconstructed burner/valve union. That said, how would one test
the soundness given it is on the low pressure side of the valve?
I replaced the spark electrodes anyway given I had the part and,
whilst I may be imagining this, the new spark certainly seems more
I am now keeping an eye on the boiler in the hope that it is either
now fine or I will catch it in the act of entering the burner lockout
state so I can determine at what stage it occurs and hence rule in/out
Any thoughts/opinion would be most welcome.
- posted 12 years ago