Worcester bosch 19/24cbi lockout problem.

[jep49]

My boiler is 8 years old. For as many years as i can remember it has had a lockout problem intermitantly. I had a new board after one episode. Now it doing it again. It appears to stem from the air pressure switch. When it is fixed to its holding plate in a vertical position the boiler goes to lockout. When i remove the switch from its holding mount and let it hang loose , everything works ok. If i gently turn it over i hear the switch click and lockout happens again.I see no sign of damaged wires or tubes. The boiler is operating ok now, but i have to have the outer casing off and the switch hanging in a flatish position. Gas engineer is baffled. For some time i thought it might be the wind. Fan is operating ok when air switch is hanging loose on its connections.Today i replaced the air switch with another one, result was the same. I am thinking of a new boiler, but dont want to be beaten by this baffling fault. Any ideas please.

 

[jep49]

Thanks for reply. I only have the outer casing off while its running of course. But i have had the inner covers off, and also had the fan out. The flu is not blocked or damaged. The rubber pipes are all undamaged. I can blow through the pipes into the fan in both pipes, and it appears to be clear. I assume the venturi is where the tubes enter into the fan area. They appear to have a 90 degree bend on at least one of them, and are hard to get at. I will have the fan out again and try to give it a better clean, but air is going through it anyway. Surely its not so sensitive as that?

 

[jep49]

Hi, Thanks to the person who replied to my original post, Lee i think. As an aside i would just add that the problem seems to be solved without having to look any further. The cap on the combustion test point on the top of the boiler was off. Seems it has been off for the last eight years, despite several services and a new board fitted without any gas engineer checking it. And at the moment it seems to be running to a more regular fashion instead of its previous on off fashion. I realise there is no discussion on diy, but maybe its worth knowing on here if anyone else has a similar problem. After all, its hardly diy to check the cap on the top. But if anyone can enlighten me as to why it has made a difference , i would be interested to know.