Oil Boiler Flame cycling

15 Feb 2020
Reaction score
United Kingdom
Oil Boiler Trianco Eurostar Premier 100/125 Condensing boiler.

Runs fine for about a minute then flame dies (sounds like the solenoid is closing oil supply) after 7 seconds it fires again and continues running. Fan is running all the while. Cycle repeats until the boiler gets up to temperature and switches off. Never goes into lock out and whilst running the CO2 etc. Are in spec.

Photocell is clean and otherwise boiler is working well.

Suspect either the solenoid or the control box, but wonder if anyone has seen this before before I order parts?
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Hi Terryworkfit, thank you! I tried this and it seems to be running fine now, I’ll keep monitoring it.

So it’s either sucking in exhaust fumes, or there’s a airflow restriction?

I’ll take a closer look at the flue this morning.
Most likely vitiated air due to flue seals .if you have FGA stick probe through the snorkel to check..
Lack of air due to a restriction would give high co2 and smoke / sooting.
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Yep, flue seal leaking. Quite a major job to sort out as the boiler has been installed “in a cupboard”. Will need to break down the cupboard first. ah well!

Terrywookfit - Thanks for your help!

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