How long can the duct run be for a bathroom fan?
The recommended maximum duct length depends on the duct diameter.
For a 100 mm duct diameter, the recommended duct run is up to approximately 90 cm.
For a 125 mm duct, the recommended duct run is up to approximately 5 metres.
For a 150 mm duct, the duct run can be approximately 8–10 metres.
Duct runs longer than recommended may result in reduced airflow and poorer performance.