Patent ID: 8905829

Claim:
A ventilating system comprising: a multi-branched duct system comprising: a main duct and a plurality of branch ducts that branch from the main duct; a plurality of exhaust devices configured to expel, to outside of the exhaust devices, inside air through venturi air valves that are connected to the branch ducts, respectively; a fan that is equipped in the main duct; and a control device configured to control speed of rotation of the fan and maintain a predetermined head of the fan, wherein: the control device sets a target static pressure value based on airflow of the entire ventilating system, calculated from the airflows of the venturi air valves of the exhaust devices during operation, and controls the speed of rotation of the fan and maintains the predetermined head of the fan, based on a static pressure within the main duct and the target static pressure value, in relation to changes in duct resistances relative to changes in the airflows of the venturi air valves.