Abstract: An improved centrifugal fan wheel adapted to receive a flow medium for radially accelerated discharge by plurality radially extending impeller blades. A plurality of flow medium passage channels are positioned radially inwardly of an outer extent of the fan wheel to improve the efficiency of the fan. The flow medium passage channels are defined by alternating cutouts disposed between adjacent blades about the outer extent of a fan wheel back plate.

Abstract: A centrifugal fan having a tubular housing in which an inlet funnel and fan assembly are contained. The fan assembly includes a fan wheel with the fan wheel inlet and inlet funnel overlapping during normal fan operation. A motor is connected to drive the fan wheel and a door is provided for access to the inside of the housing, the fan wheel assembly and motor being supported by the door for movement therewith. Within the present invention, the door further supports the inlet funnel in overlapping relation with the fan wheel inlet for movement with the door, fan wheel assembly and motor without alteration of the overlapping relation.