Hob extraction under decking?

[Super_Paulie]

Evening you fine people. Not sure if this should be in this or ventilation, but here goes. 

 

The external ventilation from my downdraft hob. Would it be acceptable to bring the vent out under my bifold doors and thus under wooden decking (not built yet) I can't really see a way to get it up a wall as the rear of the house is pretty much all door...

[Gus Potter]

Maybe but at that length of duct run BC may ask you for calculations that show that the length of duct delivers the required extraction rate. If you get asked to provide duct calculations you need to take into account not least the bends in the ducts. This can be problematic! 

 

One reason for the problem is that the extractor hood manufacturing folk don't give you the data to do the vent pipe calculations! So if you ask me to do them for you I'll charge you for the time it takes me to say get in touch with the Germans and translate all that info so that I might be able to do some calculations on and then.. into something BC can pass. Now if you take my rate at £50.00 an hour the sums don't stack up unless you really..  really want a down draft hood! Now the Germans ain't going to bend over backwards for some self one off builder in the UK..

 

If you don't believe me then just ask about.

 

If you can forget the down draft extractors. There are often other more effective options.

 

Post some drawing and folk will help you out.

 

 

 

 

Edited March 20 by Gus Potter

[Super_Paulie]

Length wise I'm only looking at 2m on the horizontal until I hit the outer wall. Might do that and get BC sign off before I build my deck...