Patent ID: 8231334

Claim:
A plenum fan for moving air, the plenum fan comprising: an enclosure defining an inlet opening, an outlet and a plenum; a frame disposed within the enclosure; a fan wheel defining a fan mouth and being supported by the frame within the enclosure, the fan wheel is rotatable to force air sequentially through the inlet opening, through the fan mouth, through the plenum, and out through the outlet; a secondary inlet cone attached to the enclosure and protruding into the inlet opening, wherein the secondary inlet cone is substantially stationary relative to the enclosure; a primary inlet cone attached to the frame such that the primary inlet cone is substantially stationary relative to the frame, and air being drawn into the enclosure by the fan wheel passes sequentially through the secondary inlet cone, through the primary inlet cone and through the mouth of the fan wheel; and a flexible duct extending between the primary inlet cone and the enclosure, the flexible duct is more flexible than the secondary inlet cone and the primary inlet cone, wherein the flexibility of the flexible duct permits relative movement between the primary inlet cone and the enclosure and also permits relative movement between the primary inlet cone and the secondary inlet cone.