Duct extractors
Extractors for fitting in the duct: axial, helical, mixed-flow units and ventilation boxes.
They sit in line, between the room vent and the outside outlet. They do not replace a bathroom wall fan.
Which diameter?
The duct’s. In a home, 100, 125 or 150 mm is usual. Boxes use larger sizes.
In-line or box?
In-line means the motor is inside the tube. A box is the centrifugal unit, for a higher flow.
Can it serve a bathroom?
Yes if the bathroom exhausts through a duct. If the unit is visible on the wall, see bathroom extractors.