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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Building Questions >> Chimney flue https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1227031614 Message started by Lectrician on Nov 18^th, 2008, 6:06pm

Title: Chimney flue
Post by Lectrician on Nov 18^th, 2008, 6:06pm

My father has had is boiler replaced and relocated.

There is now an old concrete flue which is in the chimny through to tge roof, where there is what looks like a vented aluminium cowl thing on top.

As the boiler has moves, he wants me to tidy up and decorate the area where the old boiler was. I assume I need to leave the flue vented to avoid condensation?

He also says in heavy wind and rain he gets a wet worktop under the flue. Is this likely to be driven rain entering the cowl on the roof, or possibly the mortar up there giving up? I just want a rough idea of what to expect before climbing!

Title: Re: Chimney flue
Post by JerryD on Nov 18^th, 2008, 7:38pm

It could be either problem causing the flue to leak. It is ususl to cap an unused flue with a vented insert like this:

If it still leaks then the brickwork or flashings could be letting the rain through.

Always vent the lower end of the flue as well as the top to create a drying/venting draught