Thanks again for all the helpful comments. Point taken about getting someone in to do a smoke test and FGA reading.
Yes, I do have a Tiger Loop. Regarding good suggestions about oil pressure at point of loss of flame (I will test this), dodgy drive key, slipping pump coupling, weak secondary coil, etc, wouldn't these things continue to cause a problem once the boiler has warmed up?
I don't think it's the balanced flue circulating the flue gases. The original flue started to cause this problem some years ago and I replaced it. As a test, removing the air intake hose to the burner does not improve the problem.
I am wondering if the prolonged wet weather could be behind the problem. The boiler is located in a garage with a single skin brick wall. It has a low-level rear discharge balanced flue with a total distance of only around 60 cm from the airbox to the outer end of the flue. Is it possible that driving rain has been entering the apertures into the incoming air part of the flue and lying in the flue, causing there to be heavily moisturised air going into the burner at the start of ignition after a period of non-operation. After repeated stop-starts things would dry out a bit and the boiler would run correctly. This is me going out on a limb a bit, but I do wonder. It's worth noting that there is a slight fall on the flue from the airbox to the outer end. J.
Yes, I do have a Tiger Loop. Regarding good suggestions about oil pressure at point of loss of flame (I will test this), dodgy drive key, slipping pump coupling, weak secondary coil, etc, wouldn't these things continue to cause a problem once the boiler has warmed up?
I don't think it's the balanced flue circulating the flue gases. The original flue started to cause this problem some years ago and I replaced it. As a test, removing the air intake hose to the burner does not improve the problem.
I am wondering if the prolonged wet weather could be behind the problem. The boiler is located in a garage with a single skin brick wall. It has a low-level rear discharge balanced flue with a total distance of only around 60 cm from the airbox to the outer end of the flue. Is it possible that driving rain has been entering the apertures into the incoming air part of the flue and lying in the flue, causing there to be heavily moisturised air going into the burner at the start of ignition after a period of non-operation. After repeated stop-starts things would dry out a bit and the boiler would run correctly. This is me going out on a limb a bit, but I do wonder. It's worth noting that there is a slight fall on the flue from the airbox to the outer end. J.