BG 330+ Condensing Boiler

[Mhilb]

Hello, I wonder if anyone can help please as I am at my wits end.

I have a British Gas 330+ condensing boiler. Most of the time it works perfectly fine but when there is a sudden drop in the outside temperature the boiler cuts out and there is no heating. I can restart, and after a few goes it will fire up and works for quite some time but again if there's a further sudden change in temperature outside it cuts off again. I have had numerous engineers out and they have been unable to identify what the fault is.
It comes up with F22 fault which implies that it is dry. The pressure seems fine a 1 it has had a new pump in recent times and all seems to be intact but there is something when the weather temperature changes that triggers the fault,
I have two Flues on the outside wall. The bottom one is the hot water boiler and the top one is the heating boiler when they are working hard the hot water boiler vapour pushes up and maybe getting sucked in to the top flue for the heating someone has suggested that could be causing the trigger to cut off.
Any thoughts with you very much welcome.

 

[CBW]

Can‘t see the temperature having an affect on this. F22 from ask Glow worm a question (attached image). Does you boiler have a digital display? Which reading are you taking from?

 

[Mhilb]

Can‘t see the temperature having an affect on this. F22 from ask Glow worm a question (attached image). Does you boiler have a digital display? Which reading are you taking from?

Thank you, so your reply. All ears have pretty much said the same that the temperature to affect it, but it is very odd that I can almost set my calendar by that the minute the temperature falls the boiler starts to cut out. The pressure is bar one so that seems to be okay, but nobody seems to be able to figure out what else could be the problem, but thank you anyway for your comments

 

[CBW]

Thank you, so your reply. All ears have pretty much said the same that the temperature to affect it, but it is very odd that I can almost set my calendar by that the minute the temperature falls the boiler starts to cut out. The pressure is bar one so that seems to be okay, but nobody seems to be able to figure out what else could be the problem, but thank you anyway for your comments

Which type of pressure gauge do you have?

 

[ianmcd]

I would be swapping the pressure sensor, your boiler is a rebadged Glow worm Flexicom, the pressure sensors tend to get dirt in them and read the wrong pressure, easy test there is a drain point at the bottom right hand side of the boiler, open that till no more water comes out of the drain point, and check the sensor has went to 0 Bar, then close the drain and add water back in and see if the display goes back up, if it doesnt go to 0 its blocked

 

[Mhilb]

Thank you so much for your thoughts. Strangely, it is going fine at the moment so we'll have to look at that. If it goes again, it's so temperamental.