Worcester 24i wont stay lit.

[MK Heating]

I have a Worcester 24i on a job at the moment. It goes through its cycle, lights for 3 secs or so then goes out. It will then relight it's self and do the same again. When it re lights the cycle doesn't restart, it just sparks and goes. Electrodes look ok, APS seems to be proving. Time to look at the venturi maybe?

 

[Dotty]

Sounds more like ionisation to me.

 

[Millsy 82]

Not 100% sure but check the low pressure sensor top right hand of the boiler (This may stop the boiler from lighting at all but link it out to test) The PCBs are not great on these either.

Check flame is touching the probe. Make sure you have constant working pressure on inlet of gas meter.

 

[IDCHAPPY]

If its an RSF non condensing Junior then 90% sure Millsy has hit the nail on the head with the pressure switch.
Had one do exactly the same to me.

 

[goz666]

Same as, changed the low pressure switch on one of these last week. Easy to loop out to test the theory.

Edited to add : I had to change a faulty pressure gauge as well at the same time.

 

[kris]

I know your saynig electrodes look ok , but if not ramping up then flame sensing / p switch,, check continuity from sensor to pcb, dont know how many pcb ive changed on these (alot)

 

[buckley plumb]

pcb on the one I had

 

[Whyme]

Does the fan sound noisy.

 

[arran197]

If it's an rsf, not the junior, I'd check the ignition burner pressure and inlet as a start. Also check for correct polarity and continuity down the lead from the flame rec electrode to the pcb. Also for the earth wires. If all these checks seem ok, then pcb is likely.

 

[smhstu]

Also check the aps where sensing tubes connected they tend to melt and distort restricting the air flow

 

[Deleted member 44451]

im thinking a flame sensing problem, nearly always the pcb