worcester greenstar utility 18/25 oil burner photocell can't see flame

[robbie77]

Hi

I am having problems with the oil burning boiler. I have tracked it down to the photocell not seeing the flame properly (I can start the boiler with the cell covered and if i shine a light on it once started it runs OK). If the photocell is placed in boiler as normal the boiler starts for 3-4 seconds then cuts out.The photocell is clean and under two years old.
I have taken the burner out and I think I need to move the electrode and nozzle so the photocell can see the flame better.
I have slackened off two allen key heads that attach the nozzle at the top of the burner but all this does is adjust the height of the nozzle I think.
Can someone point me in the right direction as to adjusting this!?
Thanks

 

[Agile]

I would suggest you exercise caution.

Some of those adjustments will upset the combustion characteristics.

Presumably you don't have a combustion gas analyser to check the correct operation of your boiler.

Tony

 

[bernardgreen]

I would suggest you exercise caution. Some of those adjustments will upset the combustion characteristics.

I second that.

Does this boiler have a colour sensistive photocell that says OK only if the flame is the right colour ?. Too much yellow ( poor combustion ) and the photocell will shut the burner down

 

[robbie77]

Hi. Thanks for the replys. It doesn't have a colour sensitive photocell. It looks like you can adjust the electrode gap (2.5 to 3mm) and the gap between the nozzle and the combustion head (3mm), are these the only adjustable settings?
I can get the co2, air adjustment, heat settings checked. Thanks

Thanks

 

[robbie77]

I rang my oil burner man and he confirmed not to touch the nozzle adjustment but that the electrode has a 4mm Allen Key that can be slackened and moved. So will try this later...

 

[Terrywookfit]

Just replace the fookin photocell.
Making random adjustments will fook things up.

 

[Andy4444]

Are you sure it's the cell?

Can you hear the flame establish when you shine the light into the cell?

From how you describe it I would say it sounds like there is no flame as you have proved the cell works.

RDB burners are pretty straightforward and if the cell faults the burner goes into permanent ventilation.

If no flame establishes after 12 seconds pre-purge burner locks out 5 seconds after ignition

 

[Burnerman]

Another one recommending a photocell replacement.....altering nozzle positions won't affect the 'flame seeing ability' and will come back to haunt later.
I suspect the cell isn't the right one for the burner or it is operating out of it's designed parameters.
John

 

[oilboffin]

just make sure some numpty hasn't turned the electrodes round so they are in the way of the cell
then it can't see the flame if they aren't in the cells line of sight you could drill out the hole in the
blast tube of course making sure the blast tube is on the right way round

 

[oilboffin]

By the way what burner have you got

 

[robbie77]

Thanks for the input guys. You were definitely on the right track. While sitting looking at the boiler i noticed a groove the other side of the photocell housing where the cable should route through and when i examined the photocell I could see that the bulb part (without the plastic shroud) was facing away from the flame. Some numpty (whoever fitted the boiler -don't know) had put the bracket for the photocell on the wrong way round. So I swapped it round and it is running fine! How it worked like this for last five years I am not sure. Wish I had seen this earlier before farting about it.
Appreciate the help.
Cheers

 

[Burnerman]

Good on yer, Robbie.....feedback is always appreciated
John

 

[robbie77]

Least I can do after people go out way to try and help. Lot of love out there... . I remember you helping me fix this boiler maybe six years ago John.
Thanks all

Robbie