Abstract: A Modular Fan Array of a 2×2 array of small fan modules provides many advantages over the replacement of duty of a solitary large fan, including some of the following advantages: —the combined flowrate capacity of the Fan Array can be sized equal to or in excess of the 100% flowrate capacity of the large fan, however a turndown limit of 50% will result in the Fan Array only having a turndown limit of 12.5%. There is a redundancy fan modules. With one going OFFLINE the other three can provide some measure of ventilation, while with the large fan going OFFLINE, ventilation is disable completely.

Abstract: A fan control system has a fan duct, a fan mounted in the duct, an electronic commutator (EC) motor for driving the fan, and a control system hub for controlling the EC motor. A pressure differential sensing system is mounted in association with duct and feeding a pressure differential signal to the control system hub. An input device mounted on the control system hub for scaling an output signal from a low percent extreme to a high percent extreme and sends that output signal to the EC motor. Wherein the control system hub speeds, slows or switches OFF the EC motor according to the pressure differential signal except that the input device sets a speed limit ceiling on the EC motor.