Abstract: An exhaust system for exhausting air from a space includes a variable-volume exhaust air moving system having at least one fan having an inlet and an outlet. A duct is connected to the inlet and an outlet nozzle defining a variable cross-sectional outlet area is fluidly connected to the outlet. A selectively operable bypass damper is fluidly connected to the inlet. A sensor is located in the exhaust system for detecting at least one of a pressure condition and a flow condition therein. A control system controls the at least one fan, the outlet nozzle, and the bypass damper, based on a signal sent from the sensor.

Abstract: An exhaust system for exhausting air from a space includes a variable-volume exhaust air moving system having at least one fan having an inlet and an outlet. A duct is connected to the inlet and an outlet nozzle defining a variable cross-sectional outlet area is fluidly connected to the outlet. A selectively operable bypass damper is fluidly connected to the inlet. A sensor is located in the exhaust system for detecting at least one of a pressure condition and a flow condition therein. A control system controls the at least one fan, the outlet nozzle, and the bypass damper, based on a signal sent from the sensor.

Abstract: An exhaust fan assembly is provided for expelling contaminated air from a building. The assembly includes fan housing connected to the building via a duct. The fan housing contains a fan the draws air from the building through the duct. An extension is mounted to the outlet end of the fan housing, and has a cylindrical upper end connected to a nozzle. A windband is connected to the upper end of the nozzle, and provides an air entrainment path that allows ambient air to mix with the exhaust air prior to exiting through an exhaust fan assembly outlet.

Abstract: An exhaust fan assembly is provided for expelling contaminated air from a building. The assembly includes a plenum, a fan assembly attached to the plenum, and a windband mounted on top of the fan assembly. The fan assembly is constructed of cylindrical outer and inner walls which define a bearing chamber and surrounding annular space. A fan driven by a shaft extending downward from the bearing chamber draws exhaust air from the plenum and blows it up through the annular space to a nozzle at the top of the fan assembly.