Boiler flue extension DIY?

3 Jan 2009
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United Kingdom
Hi all,

I have a boiler flue exiting my house wall. Hot gases from the flue are continually setting off the security light PIR which was recently installed by a (clearly somewhat dopey) electrician. See photos attached.

I have considered moving the light (or the PIR), but the gases would probably still be 'in view' of the PIR, unless I put it in a very distant location which would then compromise its field of view for detection of burglars!

So I'm thinking that it makes more sense to vent the flue at a slightly higher level by installing an extension pipe with a 90-deg bend, perhaps 500mm long? That will mean the gases all go 'upwards' rather than 'outwards'.

Can anyone advise whether it's possible to do this DIY? The flue exit pipe seems to be 100mm diameter.

If it's not permitted, what's a likely cost for this today from a tradesman?

Thanks very much!


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Thanks Swwils. I assume that microwave sensors won't be reflected off the steam.

Is it possible to buy a separate small microwave sensor that I could swap for the existing PIR?

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