Cooker hood extractor venting

[Pufter]

I've fitted a hotpoint extractor hood from B&Q. Where this is fitte

there was an ordinary extractor fan venting to the outside through th cavity wall via a 100mm PVC pipe. I want to vent the new cooker hoo through the existing hole, but the top of the extractor has a 150m round outlet. What is the best way to reduce this to 100mm to ven through the existing hole (which is at 90 degrees to the extractor s flexible conduit required). I've seen a 125mm to 100mm PVC collar i Screwfix, but not 150mm to 100mm anywhere. Mkaing the hole in the wall bigger is not really an option! Thanks

-- Pufter

[Pufter]

I've fitted a hotpoint extractor hood from B&Q. Where this is fitte

there was an ordinary extractor fan venting to the outside through th cavity wall via a 100mm PVC pipe. I want to vent the new cooker hoo through the existing hole, but the top of the extractor has a 150m round outlet. What is the best way to reduce this to 100mm to ven through the existing hole (which is at 90 degrees to the extractor s flexible conduit required). I've seen a 125mm to 100mm PVC collar i Screwfix, but not 150mm to 100mm anywhere. Making the hole in the wall bigger is not really an option! Thanks

-- Pufter

[Pufter]

I've fitted a hotpoint extractor hood from B&Q. There was an ordinar

extractor fan venting to the outside through the cavity wall via

100mm PVC pipe so I want to vent the new cooker hood through this, bu the top of the extractor has a 150mm round outlet. What is the best wa to reduce this to 100mm to vent through the existing hole (which is a 90 degrees to the extractor so flexible conduit required). I've seen 125mm to 100mm PVC collar in Screwfix, but not 150mm to 100m anywhere. Making the hole bigger is not really an option! Thanks

-- Pufter

[Lobster]

Try

- they're normally the best place to try for this sort of stuff.

David

[Mark]

Look at 11494 - 125 mm i.d. to 100 mm o.d., white and 11495 - 150 mm i.d. to 125 mm o.d., white

Bear in mind that 100mm dia pipe will create much more back pressure than 150mm pipe!

Mark.

[Bob Mannix]

You should worry! My toilet extractor fan (Xpelair) vents through a 75mm pipe that runs through the flat roof to the fascia about 3-4m. You can't buy extractor fans with smaller than 100mm outlets now (not that I can see). I can't shove a bigger pipe through as it's full of insulation. Meanwhile the fan bearing gets noisier and noisier :o( Any suggestions, likewise, welcome!

My kitchen extraction also runs parallel in 75mm pipe for about 2m. I had to convert right down to that - it still extracts enough but much slower than it would with a bigger pipe, and much noisier. The flow is also non-linear with fan speed, there's no point running it other than at the first position as the noise goes up exponentially and the extraction just a bit!

[Mark]

Can you take out some insulation and then run a 100mm pipe through? If you can't do this you could look at reducing the speed of the fan or buying a stronger fan!

I found it worthwhile to replace the pipework in my kitchen with larger diameter round pipe. It made a big difference.

Mark