Patent ID: 8814639
Filing Date: 2014-08-26
Classification: F04D,F24F,Y02B

Abstract:
1. A fan system for a variable air volume air handling system that supplies conditioned air to a structure having multiple zones, wherein the air handling system includes a duct system for distributing air output from the fan system to each of the zones, a duct pressure sensor, and at least one fan speed control for controlling the speed of the fans in response to the duct pressure sensor to maintain a desired system pressure, the fan system comprising: a fan array comprising a plurality of independently controllable fan units configured to operate in parallel to blow air through the duct system, wherein each of the fan units comprises a backflow preventer, wherein each of the fan units is a plenum fan, wherein the backflow preventer comprises a disk supported in the fan wheel housing for movement between a closed position in which the disk blocks air from flowing through the fan and an open position in which the disk allows maximum air to flow through the fan, wherein the wherein movement of the disk is driven by air flow so that forward airflow through the fan when it is operating drives the disk toward the open position and so that backward air flow through the fan when the fan is not operating drives the disk toward the closed position, and wherein the backflow preventer comprises means for biasing the disk toward the closed position; an automatic fan control system comprising: