Extractor ducting difficulty

[regsmyth]

In a new kitchen, trying to work out the best way for extraction.(Not sure if this is the most appropriate forum, but I'll try.)
The steel in the ceiling/floor is in the way of any "normal" hood.
I have tried to pull apart some hoods in the sheds, to see if it's possible to do without the top "chimney" section, or to take the outlet pipe from an off centre position (to run vertically up into the void, then left) but always get thrown out.
I could do what I show in the drawing (ducting would be left exposed),but maybe the bright sparks here know of something better, such as a ceiling mounted unit, complete with fan, with an offcentre outlet?
I'll be looking for extraction rates of min 300m3/hr, which rules out most of the flat recirculating type.
I don't want to take the outlet through the wall below the steel mainly because I think this will compromise the structural integrity of the wall.
Any thoughts or suggestions welcomed!

 

[JPC]

i dont do much on ventilation, however does it need to remain 100mm diameter or could it be reduced (as not dangerous and fan assisted) to a smaller bore pipe ?...would that help.

if worried about the integrity of the back wall (is that cos the steel is there?) could you not put in a small lintel and then put the hole under it ?

how about a filtered fan ?

 

[ChrisR]

Drop the end wall cupboards so the top lines up with the others
Red's a stainless, white or woody panel, maybe with downlights
Green's your exhaust, hidden behind Pinky cornice running along panel front and round all the cupboards - including those not shown on plan!

View media item 930

See BES, search on ventilation.
Plenty of this sort of clobber:
http://www.bes.co.uk/products/graphics/11407.gif

 

[regsmyth]

I will check out BES thanks.
The thing on the right is a window!!