Sealing a Flue

26 Oct 2014
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United Kingdom
Hello All,

First post here. I have an old boiler that had been labelled as 'at risk' due to the flue not being sealed. This was found following an external gas leak. I know little about gas regs and I was told to cpntact an engineer to have it checked but I have a three week wait.

Our boiler is a floorstanding Mexico with a flexi flue that runs vertically up three floors of disused chimney. I can only access the front of the boiler due to stonework/plasterboard blocking all other access however, I managed to stick a camera in a hole and noticed that the flue runs up the chimney with no 'plate' filling the void between flue and brickwork. The pic will explain it better.

Is it essential to have a seal in this area ? If so is its purpose to keep the exhaust fumes from returning to a sealed room in a backdraft? What meterial is it made of?

Thanks for any help. I am considering all options as if I do need to fit a seal then the boiler will have to come out anyway....... and I may aswell get a new one.

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Rock wool will do it but technically if thats all it needs its NCS not at risk so can be used

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