Cooker Extraction Hood - thoughts and ideas please

[Carrerahill]

Hi all.

 

As part of my first fix I need to bottom out the cooker hood, I have already included a piece of soil pipe through the wall when it was built which ends in the service void for now, slightly pitched to the exterior. The service void, which the duct will need to pass through will be plaster boarded over on Thursday/Friday and plasterer is booked for the 3rd of Jan so I need to bottom it out really before Christmas so I can order any bits now.

 

I attach a sketch of the situation, idea is, obviously, hood above the hob, I can get the stainless duct I want and even the bend with the same pitch as the ceiling so the duct can sit parallel to the ceiling and it will go up via the service void to the outside. My thoughts were either, inline fan in the void, so the hood is just that, a hood, or a hood with the motor built in and just push the extract up the duct and out.

 

I am tempted to have it custom fabricated and then I will incorporate a control and lighting but obviously off the shelf stuff would be easier. 

 

I can find images of what I want, but struggling to find who actually does something that would work, and not really being a cooker hood aficionado I am not entirely sure of the usual connections etc. Do the external venting hoods simply have a 4" (?) spigot for connection to various ducts etc, condensate drain somewhere?

 

See attached a sketch and 2 images showing the idea of what we are going for.

 

One option I have is to simply extend the piece of soil pipe out through the, yet to be installed, plasterboard and leave it sticking out then when it comes to duct install and hood etc. then I just need to get the duct up to the pipe and probably incorporate a small stainless flange to clean off the edge. Down side to this option is that I then lose the opportunity to put an inline fan into the void before PB goes up, but then, do I want a fan in a void, probably not as I don't want an access hatch which would then be the stupid design of a fan boxed into a void - bad plan!

 

I suppose if I went down the self fab route then I could get the hood made up then have a good quality fan incorporated into the hood so all the M&E is incorporated into the hood which can be serviced easily.

 

So if anyone who has recently had cause to procure and spec up a hood, what did you do, how did you do it and who did you use.

 

Thanks

 

 

 

 

 

 

Edited December 17, 2019 by Carrerahill

[Mr Punter]

I have done a couple like this using 150mm galv metal tube which looks the same diameter as your 2 photos.  Mine have a very slight fall to outside.  100mm diameter is too small imo.

If you can, an external fan really cuts down on noise.

[wozza]

You will find that any decent extractor hood will require a 150mm duct (or rectangle equivalent) - my last one was 150mm but the instructions said that a 125mm duct could be fitted as the minimum - It was a Luxair

 

From the Luxair site:

 

Cooker Extractor Hood 4" 100mm Ducting System

100mm Ducting is used for low power cooker hoods, generally any cooker hood with a motor extraction rate of between 150 m³/hr to 450 m³/hr, most cooker hoods back in the early 1980s had very poor extraction rates and 4" ducting was the normal dimension used, even today some cheaper cooker hoods will allow for 100mm ducting to be used without any problems, Luxair also produce some models that can be used on 100mm ducting however we always recommend that you check out our technical information on each product page as this will determine what size ducting you will require for each model based on the size of the motor. 

 

https://luxairhoods.com/100mm-cooker-hood-ducting

Edited December 17, 2019 by wozza