A back draught shutter is a device designed to prevent air from flowing back up the ductwork and into a room when a mechanical ventilation system is not in operation. This is particularly crucial in winter to maintain indoor temperatures and prevent cold air ingress.
Back draught shutters can be integrated into the fan unit or installed as standalone units within the duct system. When integrated, they often consist of a simple one-way hinged membrane that opens when the fan operates (allowing air to flow out) and closes when the fan is off, thereby preventing reverse airflow. In some advanced systems, these shutters may be controlled thermally, responding to temperature changes to enhance energy efficiency.
Standalone back draught shutters are frequently used with centrifugal fans, offering flexibility in installation locations throughout the duct run. These shutters are essential in ensuring that the ventilation system operates efficiently, particularly in climates that experience significant temperature fluctuations.