I am currently in the process of having a kitchen fitted by a couple of very good Polish builders who speak very little English.I recently purchased a
conventional Extractor and the builders have said it would be far better
to remove the air outside plus there is already a large vent hole where it will
be positioned. I rang the company where i bought the extractor / Kitchen
and they said I would need 2metres of ducting tube/2 Jubilee clips/a through wall tube + a non return valve. When i described this 2 my builders they looked at said no you just need a pipe from the extractor to the outside?

any takers on what both parties are on about ?

I no nothing about this -help