Gas boiler leaking water down the wall from flue.

[Ian Stirling]

On investigation, I found that my balanced flue gas boiler is, in the face of moderately blown rain from the east, having rain blown through the inlet (probably aided by air inflow when it's running).

This then drips down behind the fan and runs down behind the boiler through mounting holes, and makes horrible stains on the wall. Not to mention that it's probably not awesomely electrically safe, though I've never noticed wet wiring/boards.

I initially thought that this was a problem with rain getting through outside the balanced flue, which would have been fairly east to sort.

I could bodge it with some silicone, so the water runs away relatively harmlessly, but...

Should the balanced flue be sloping down away from the boiler (24" wall) I suspect it's level (not checked), which would be a major job to change.

Do plates that go over the end of the balanced flue, and exhaust downwards, so no windblown rain can get in?

[Lee]

The installation instructions for our boiler flue say it should be installed, "..with a 1 degree fall to prevent rain water entry".

Not that I can see how 1 degree makes any difference.

Lee

[Ian Stirling]

It'll make water tend to run out, rather than pool, or run in.

It's 10mm in a 600mm wall, for example.

[Lee]

(grabs calculator), So it is....didn't realise it was that much when I posted it. :)

Lee