Patent ID: 9689585
Date: 2017-06-27
CPC Classifications: F24F

Claim:
1. An HVAC system, comprising: an HVAC unit including a climate control system configured to control the properties of a flow of air passing through the HVAC unit and an air mover adapted to create a pressure differential between an inlet and an outlet of the HVAC unit; a supply air duct in fluid communication with the outlet of the HVAC unit; a return air duct in fluid communication with the inlet of the HVAC unit; a plurality of zones positioned between the supply air duct and the return air duct, wherein each zone includes a climate controlled space; a bypass duct extending between the supply air duct and the return air duct, wherein the bypass duct includes an active bypass damper having an open position, a closed position, and a plurality of partially opened positions; a pressure differential sensor configured to measure the pressure differential across the bypass damper; and a control device configured to determine the actual flow rate of the conditioned air flowing through the bypass damper in response to measuring the pressure differential across the bypass damper, calculate a recirculation ratio equal to the ratio of the actual flow rate of the conditioned air flowing through the bypass damper to a nominal flow rate of conditioned air generated by the HVAC unit, compare the calculated recirculation ratio to a bypass air flow threshold, and at least one of (1) adjust the position of the bypass damper in response to determining that the calculated recirculation ratio exceeds the bypass air flow threshold and (2) maintain the position of the bypass damper in response to determining that the calculated recirculation ratio does not exceed the bypass air flow threshold.