Oops is there an edit on here, also meant to say the Lux air seems to
say 'Please Note: Chimney Stack with vent must be used when
recirculation option is used'

I am not able to use ducting, so what does this mean exactly?

I'm guessing it is badly translated and actually meant

say 'Please Note: when Chimney Stack with vent is used,
recirculation option must be used'

i.e. meaning that if you can't have ducting, then all the hood will do is
blow moist greasy air around the room and turn itself rapidly into a health
hazard.

Christian.