Worcester greenstar utility 18/25 oil constantly locking out.

6 Nov 2008
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United Kingdom
worcester greenstar utility 18/25 oil constantly locking out before it runs.

I am having problems with the oil burning boiler again. It is locking out all the time and has been for few weeks.
The boiler will sometimes fire and run but more often than not it won't fire at all - tries for a few seconds then stops. Reset button might need to be pressed 4 or 5 times before firing, some days better than others.
Have had the jet replaced and the photocell replaced.
Baffles and tank cleaned.
Filter on oil tank is less than 1 year old.
Plumber has checked/ adjusted the C02 reading etc .

I replaced a coil on it a few years ago but the symptoms were different - would get warm then stop. This has problems just starting.
Is it worth replacing anyway?

What else can I try.
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I think the motor is spinning OK mostly? I mean when I press the reset button I can hear it. I can check the capacitor though so thanks.
Interesting. I have checked the UF value of the capacitor and it gave a reading of 1.9 and the rating is 3UF so maybe this it as I think the tolerance is 5%?
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Yeah It is producing spark OK. It will sometimes run for an hour OK so will that rule out oil flow issues???
I have just:
1.Opened the pump to see if there is any dirt- it was clean.
2.Looked down the blast tube and made sure the HT leads were not blocking the photocell - there doesn't appear to be any adjustment on the electrodes to move them but looked OK?
3. Moved the photocell bracket around to see if that helped -it didn't
Is it worth checking the oil flow? Is there an easy (basic way). I just cracked the nut off at the bottom of the pump to bleed it and seems have good pressure?
another observation is that often when it does fire, it will run for a few seconds and then lockout. So I can hear the motor/fan, electode click, pump solenoid, fire and then dead. Sound like fuel supply? Maybe disconnect fire valve and check flow outside?
Second that. If it fires for 5secs it's photocell. Is the blast tube dirty? What version control box have you got? It'll have numbers on it
It's a Bentone DKO 970. The plumber had a spare control box he leant me and it did the same. I have put the old photocell back in and will try that.
You can just make out the tip of photocell in this photo. The plumber said you can sometimes move the electrode holder thing and there is an allen bolt on the arm that looked like it might move if I loosened it but I put a hairline crack in the cermaic of one of the electodes trying to wiggle it and stopped so that will probably need replacing.
oil jet.jpg
Urghhhh. It still fires sometimes and is no worse at moment from what I can see.

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