The essentials of exhaust fan performance from Fasco Asia Pacific

For an exhaust fan to perform at maximum efficiency, the key requirement is a balanced airflow. This means that the volume of air being exhausted by the fan must be matched by that flowing into the room. The source of this in-flowing air is most usually an opening (vent or grille) in either a door or wall. Whatever the source, however, it is vital that it be located as far away from - and opposite to - the location of the exhaust fan. This will encourage a "cross breeze" which is essential to clear either vapour or odours.

No exhaust fan will effectively extract air from any room which does not have provision for return or replacement air. (Generally speaking, the gap under a door is inadequate and the installation of a door grille is recommended to ensure the necessary air supply). In all installations, the exhaust fan should be so positioned that the airflow generated progresses