I'm hoping this is the right forum for this question. I need an extraction system for an internal cloak room toilet. The ducting will be above the ceiling for a distance of 2m in a straight run. The extraction unit will be mounted in the ceiling and will have 1 90 degree bend. Any suggestions on a decent and relatively silent system? Because there is only a toilet and a sink (no shower) can I use a unit that is for zone 3 ? If the ducting is above the ceiling do I need to box in?An electrician (currently on holiday so I can't ask him) will be installing electical work whilst I do the rest.