Venting Route for Extractor hob - Is this possible?

[Cellophaneskies]

Hi

I'm looking to have a extractor hob installed. A standard hood can't vent outside as the floor joists run the wrong way and there is also a lintel in the way!

Al the stuff online I see demonstrates the routing for the ducting as either going back under the unit and out into the room as recirculation, or if it vents outside, it all assumes that the hob is backing onto an external wall. The ducting comes out the rear, back down the back of the unit, and then goes outside the wall it is against.

I need to go outside the back of the unit, turn 90degrees to face away from the unit, and then straight out to the wall. The other complication is that this is right next to my neighbour's front door, so it's a bit rude having my fumes and smells right next to her door. So it would be better if I could also route it away from her wall, but I'm not sure can use that many 90 bends? I think the advice tends to be 5m max run, and lose 1m for every bend. So I'd have 2 bends just to get out of the hob, and I'd be adding 2 to get it further down the wall,..

Anyone have any advice or experience?

 

[Tigercubrider]

I believe that extracts have a stated maximum distance in their specs?
And that every bend limits the max length by a factor of “X”

However I didn’t know if X is the same for all/ varies by duct material

My kitchen extract comes out the side, and I made a “shelf” from a kitchen end panel that faces downwards, supporting the duct to travel maybe 2M. It goes out as in your first picture. Then it’s boxed in with ply to match the ceiling.

My hood could be vernted out either side or the back. I had to cut the stainless side.

Maybe it’s possible to add a second fan inline for the bend?