Abstract: A dual conveyor jet impingement oven having a blower box with at least one air inlet opening and at least two air outlet openings and a heating space adjacent to and in fluid communication with the blower box. Disposed within the heating space are two spaced apart pairs of spaced apart heated air distribution plenums, which form a central return air conduit therebetween. The central return air conduit has a return air outlet end in fluid communication with the blower box and the spaced apart heated air distribution plenums have a heated air inlet opening in fluid communication with the at least two air outlet openings. A horizontal heating surface is disposed between each pair of spaced apart heated air distribution plenums, each of which has a perforated heated air distribution plate facing the horizontal heating surface.

Abstract: A conveyor oven is described having increased efficiency from enhanced flow therethrough. The oven consists of an upper plenum, a lower plenum, and a return plenum. The upper plenum is disposed above the conveyor and dispenses heated air through nozzles downwardly. The lower plenum is disposed below the conveyor and dispenses heated air upwardly. The upper and lower plenums are tapered from a maximum width of 21/2 inches to a minimum of no more than 15% thereof across the path of travel of the conveyor. A blower having a vertical axis of rotation is located at a midpoint between the upper plenum and the conveyor and a burner is located below the inlet between the inlet thereto and the return plenum. The outlet from the blower directs air through scrolls onto a baffle plate having rounded edges and from there into the upper and lower plenums.

Abstract: A ventilation assembly (10) for buildings (12) such as livestock barns economically and reliably prevents fan motor operation below the minimum speed required for removal of excess moisture and harmful pollutants from a ventilated building and for adequate motor cooling and lubrication. A preferred embodiment includes a fan unit (14) having a fan (18) motor (20), and a speed-responsive centrifugal switch (22), and also includes a speed control unit (16) having a temperature-responsive speed controller (24) and time delay override relay (28). In operation, the centrifugal switch (22) activates the override relay (28) if the motor (20) drops below a predetermined speed for bypassing the speed controller (24) and impose direct line voltage on motor (20) in order to increase its speed to its maximum for a predetermined time as determined by the time delay setting of the relay (28).