Installing A Non Return Valve In The Kitchen Extractor Pipe Where It Joins The Community Pipe.

[BarnaWill]

Hi all -

After many many complaints by She Who Must Be Obeyed, I need to install a non-return valve in the kitchen extractor fan assembly, so that we don't smell the neighbours' sometimes-very-odd cooking smells when their kitchen extractor fan is on, and ours isn't.

(It filters down through our system and stove extractor and is pretty horrible, sometimes, to be fair. Sometimes they cook at midnight or 1am and it smells like boiled feet).

I've ordered a non-return valve (https://ibb.co/YDcLjsb), but I'm wondering exactly where to install it - precisely where - at the junction of our kitchen exhaust tube where it meets the community / building exhaust pipe.

Also, I'm presuming it has to be installed exactly level, which is going to present a bit of a challenge, as you will see -

Our kitchen out-pipe is the one on the left in this pic: https://ibb.co/GWPkBTS
Another pic of our pipe: https://ibb.co/frwR2Z7

Comments / advice gratefully received!
Thanks in advance.
Will

[BarnaWill]

[Hmm. Links in parenthesis appear not to work, even to an approved image site.]

[Buenchico]

Links need to be clear of all other text in order to work. (i.e. they need a space, or a line return, before and after them). Here's your link:
https://ibb.co/YDcLjsb

[Hymie]

Here is an example of a duct valve/damper available in the UK.

I think they operate by being finely balanced between open and closed, such that a small backdraught causes it to close automatically, and therefore its mounting orientation is likely to be critical. I suspect this one needs to be mounted horizontal.

But I personally doubt that such a damper will close in your application, as there is likely to be a very small reverse airflow letting the smell into your dwelling – this type of automatic damper is designed (for the most part) to stop external wind (airflow) entering the property when the fan is not switched on.

Such valves/dampers are available with manual or motor operation – I suspect you will need to fit this type of valve/damper, but at least the orientation won’t be critical to its operation.

https://www.bes.co.uk/domus-straight-pipe-connector-damper-100mm-white-15665/

[davebro]

yes - being able to physically shut it when you're not cooking sounds like a good plan.

[bhg481]

Looking at the valve the axle needs to be horizontal but, so long as the output is higher than the input, it should work OK as it's just gravity operated.
If you disconnect the flexi pipe at the wall, fit the valve there and then re-connect the flexi pipe to the outlet of the valve I think you'll be OK. It might mean a bit of creative engineering and use of gaffer tape on the flexi pipe connection but no serious building work is complete without gaffer tape.

[The Builder]

I agree with fitting it just the other side of the wall on 'your' side so that it's as near as possible to the main stack.

Do bear in mind though that there's no guarantee of complete success. I say this simply because the whole system is badly designed.
A generally good rule to follow with extraction is to never combine sources. Extraction works much better when each origin has its own dedicated stack and outlet.
If that rule can't be followed, then connections should be 'offset' as much as possible. Otherwise, 'crossflow' is inevitable.

Worth a shot though :o)

[BarnaWill]

Thanks guys, good suggestions.

[Hopkirk]

An alternative, though not ideal, would be to leave your extractor on all the time - or whenever they are likely to be cooking.