Kitchen cooker hood extractions via existing fan ducting

[GregaMB]

I've had a new build and my very capable builder decided to use filtration cooker extraction hood instead of guiding air outside of the building. Instead of that it installed internal ceiling extraction fan ducted to outside. This ceiling fan is always on at about 6l/min and can be turned/boosted on 13l/min.

The hood itself supports both modes so I'm thinking of ducting this to the outside of the building.

I'd like to avoid cutting through the walls of the house and creating new ducting, instead I'm thinking whether it would be possible to use existing (fan) ducting?

My thoughts are to use one of the ducting Y pieces and maybe a couple of dampers to prevent air flowing the wrong way.

Is this feasible or could just create problems down the line?

The quick sketch would be something like this


Extractor hood -->--->-->--Damper-->->-\
\
--->----->---->Outside
/
Existing ceiling fan -->--->-->--Damper-->->-/

 

[foxhole]

Regulations require kitchen extract to be routed outside, recirculaton not permited , unless you have air management system , do all rooms have ceiling vents?

 

[GregaMB]

Regulations require kitchen extract to be routed outside, recirculaton not permited , unless you have air management system , do all rooms have ceiling vents?

Yes, this is the probably the reason why they installed ceiling fan in the kitchen.
I have ceiling fans in all of the wet rooms (WC, Utility, Bathroom, En-suite,Kitchen) and windows with vents in all of the other rooms.

 

[Burnerman]

I have seen this set up before, two fans using one duct......it was ok so long as both fans were on at the same time.
John

 

[foxhole]

Depends what’s been used for ducting , kitchen hood unlike the rest needs heat resistant ducting, ordinary plastic hose will disintegrate very quickly .