Oil Boiler cuts out constantly

[Lareon]

When I bought my house last year the central heating system would cut off constantly at the boiler
(lockout light would be on)

the setup is

Oil boiler camray 5 65/90
Burner Riello RDB

I had the boiler serviced and it seemed fine to start with, the problem was gone. Then as the weeks go by it starts to lock out once a day now it locks out every hour sometimes more sometimes less

sometimes just pressing the button works and it fires straight up. sometimes i have to press once or twice. sometimes it feels like i have to press the limit reset and then press the lockout button (could be coincidence that works though)
usually after pressing i hear the boiler fire up. sometimes when i press it i hear it whirring then it locks out again (usually works second attempt though)

the service included,
new filter
Nozzle
flex hose
cleaning the baffles
adjusting pressure on expansion vessel
adjusting air oil ratio? i think

If there was anything else i can't remember.

I've kept the pressure at 1.5bar or just above as the pressure does drop very slowly over time (i think one of the pressure regulating cartridges has a little leak on it, will replace that soon)

where do i start looking to diagnose this?
I've tried to be thorough but if any more information is needed let me know.

 

[oilhead]

Is it balanced flue? Access cover seals often leak on these, feeding the burner with contaminated air. At low levels, you get constant reignition which you may not notice as these boilers are fairly quiet. Could also be photocell, or fuel problems. Call your engineer back, or another if you feel he's not much good.

 

[oilboffin]

Take off the tube which feeds the burner air and if it runs ok your flue is faulty.Bob

 

[Lareon]

Thanks guys, the flue isn't a balanced flue, it's a vertical chimney type.

the engineer is there today having a look at it.

When i get home if it's still not working i will test the air tube myself

Then i might call an engineer and describe what you guys have said.

Thank you, will update when i know more

 

[oilhead]

That is a vertical balanced flue

 

[Lareon]

That is a vertical balanced flue

Ah thanks! my mistake

 

[Terrywookfit]

Are you sure the motor runs every time and not just buzzing (Stalled)

Sounds like typical symptoms of a sticky oil pump and / or faulty capacitor.

 

[Lareon]

Are you sure the motor runs every time and not just buzzing (Stalled)

Sounds like typical symptoms of a sticky oil pump and / or faulty capacitor.

It doesn't run every time no, sometimes it just buzzes and the second or third attempt it usually starts up, last night i tried 4 or 5 times with no luck, which is the worst it's been.

I'll check the capacitance and have a look at the pump too.

 

[oilboffin]

Either capacitor or pump goosed.By the way damm good boiler boulter camray 5 keep the inhibitor topped up and it'll last for years.Bob

 

[Lareon]

It was the capacitor. working great now cheers guys!