is of any shape and preferably has a generally concave arcuate shape the sidewalls 46 are pivotally mounted to walls 48 in duct 34 by a stub shaft 50 that extends through a pivot bearing 52 mounted in openings 54 in walls 48 a handle 56 is connected to at least one stub shaft 50 outside of duct 34 alternatively a motor not shown is connected to the stub shaft 50 mounted to wall 48 adjacent handle 56 is a locking mechanism 58 that retains handle 56 in a desired position in one embodiment mounted to the interior of the duct 34 is a first stop 60 a strike bar 62 and a second stop 64 each of the stops 60 and 64 and the strike bar 62 have seals 66 attached thereto in addition on the interior of wall 48 and on a corner edge 68 of the diverter assembly 42 are aligned strips 70 of slidable material such as uhmw polyethylene that allows the diverter assembly 42 to slide in relation to wall 48 in operation when fans 38 and 40 are activated air is blown through intake opening 36 to the diverter assembly 42 when the diverter assembly 42 is in a raised or first position air flows through lower opening 30 into bin 12 and through upper opening 32 into bin 14 when in the raised position back edge 72 of diverter wall 44 engages second stop 64 while front edge 74 engages strike bar 62 to seal duct 34 to change the direction of air flow the diverter assembly 42 is rotated by handle 56 or motor to a lowered or second position in the second position air flow is diverted from fan 68.