Air pressure switch filling with water!

[The Gallery]

Worcester 350 RSF (20yrs old)
About 18 months ago my boiler was failing weekly and the engineer that got it working said my fan needs replacing ASAP.
Paid to get fan fitted with a different engineer as Scottish gas said they couldn't get the part but problem persisted.
Another Scottish gas engineer said it must be the air pressure switch so I also got that changed.
No difference and problem remained until a different engineer (given up on the first guy) noticed moisture in the silicone hose that goes between fan and switch.
After 3 visits he couldn't find how moisture was getting into the hose but he sort of fixed it....
Turned the air pressure switch upside down so the hose was now higher than the AP switch and the fan preventing any moisture gathering in the hose.

So yesterday after a year of working it failed again, my engineer has just been to check and yes you guessed it... no water in the hose but the air pressure switch was half full of water!
He's emptied and dried it but doesn't know why it's happening!
It's working again but only until the AP switch fills with water again.

So my question is... how or why would moisture gather in the hose or air pressure switch?
Previous 2 engineers just keep checking the flue but not much else.
BTW It's Scottish gas who also service it annually.

Thanks

 

[wull67]

Your problem could be condensation in the tubes/aps, I've fitted a deflector plate on a Worcester before for this problem (think it was the 28 si boiler) cured the problem which on previous history was happening only in colder months. Ps don't know if Worcester do this for your model

 

[Gas2Air]

Rain?

 

[Agile]

I have also occasionally encountered condensation in the APS hoses on older Worcester boilers.

It was never a big problem so I never needed to engage in significant fault finding on them.

Don't remember that problem on any other boiler makes.

Tony

 

[The Gallery]

I'll assume then from both these replies that the only way water (condensation) can enter the tubes APS is from water ingress at the flue.
That's obviously something I can check the next time it rains but it seems strange that after 19yrs it's just started to happen!
It's only a very small amount that gathers in the APS over a long period of time so it might be difficult to detect though.
Is it only if water accesses the flue directly or can it be caused by broken mortar around the flue vent?
I did notice some loose mortar under the rubber seal where the flue protrudes from the wall!
Does it require a perfect watertight seal in the brickwork?

Thanks again

 

[Agile]

There can be a lot of different reasons.

Over flowing gutters.

Tight people who run heating or hot water for a few minutes so the boiler does not get properly hot.

Tony

 

[The Gallery]

There can be a lot of different reasons.

Over flowing gutters.

Tight people who run heating or hot water for a few minutes so the boiler does not get properly hot.

Tony

Gutters are fine and boiler is run for long periods of time.

 

[Steelmasons]

I have also occasionally encountered condensation in the APS hoses on older Worcester boilers.

It was never a big problem so I never needed to engage in significant fault finding on them.

Don't remember that problem on any other boiler makes.

Tony

Halstead suffered as did a few others..

 

[wull67]

If it is condensation it's caused by the colder air being pulled in by the boiler meeting with the milder air in the aps tube, not normally to do with rain water as the position of the Venturi would make it difficult for rain water to get into the tubes, my understanding anyway

 

[bernardgreen]

Horizontal rain ? Is there any corrolation between boiler failing and high winds that could be blowing rain into the air intake ?

 

[petit_pablo]

It will be condensation building up as opposed to rainwater. The position of the venturi/APS and the physics of rain being driven in are nigh on impossible.
As to how you get round this, im not sure. Not a problem ive had too often.

Wheres the boiler fitted? In an unheated space or within the heated part of the house?
A new boiler doesnt have an APS