100mm Gravity Shutter Black – 4 Inch Extractor Fan Vent

Description

The Knightsbridge 100mm gravity shutter is a black polycarbonate vent cover with three internal louvres that open under airflow and close by gravity when the extractor fan stops. Designed for installation on both internal and external walls, the shutter accepts 100mm rigid or flexible round ducting from standard 4-inch extractor fans.

When fitted to an external wall, the shutter prevents rain penetration and backdraught air from entering the ducting when the fan is off. The gravity-closed louvres also block vermin and windblown debris from accessing the duct run. In internal wall applications, the shutter acts as a one-way valve that allows extracted air to pass through to a plenum or adjacent space while preventing reverse flow when the fan is not running.

The 152mm square faceplate fixes directly to brickwork or masonry using screw fixings through the four corner mounting points. The 22mm recessed depth allows the shu