Water running down vertical boiler flue

[bill_robertson]

Hi

I have a Vaillant Ecomax boiler installed upstairs in a cupboard with a vertical flue running up through a pitched roof.

When its windy and it rains water seems to be running down the ouside of the flue and sitting on the top of the boiler. I've had the roof checked on several ocassions with no evidence of any problems. As this only occurs in windy conditions my theory is that rain is getting driven into the flue.

Can anyone offer any ideas as to why the water seems to be running down the outide of the flue? (incorrect flue installation?)

Thanks

BR

[Dulwich]

I've had a similar problem with a Vaillant Ecomax. I have mine in an attached garage under a flat roof. New boiler and new roof only 2 years ago and the roof checks out OK.

I had a drip tray under it and sometimes after it had rained it have collected water and other times it would not. I could never work out the exact criteria that had to prevail to make it drip. And I never caught it in the act so to speak - just that sometimes after it had rained would there be water there. Other times there would be. Now that you mention it, a wind & rain combination could well be it.

I'll monitor it more closely again in future and will keep you posted.

[Andrew Gabriel]

Guessing here, but water that get into the flue pipe will run down the inside wall, and at each joint will tend to be transferred to the outside of the flue pipe if the joint is not perfectly sealed.

[Cantor]

Yes, thats my guess too!.......I've now spoken to Vaillant tech support and they confirm that any rain driven into the flue should flow into the condensate drain. So, it looks like at least one joint in the flue isn't correctly sealing.

Thanks

[robert]

The joints on the outside of the concentric flue pipe dont appear to be designed for a perfect seal - the pipes but together and just have a clamp/sleeve over them. Robert