Series G4-68, Y4-68 centrifugal fan manufacturers is suitable for matching the steamed professional boiler that below 230t/h. G4-68 can also be used in the well, if there is no particular condition. The media of the transmission is air and the permissible highest temperature should be less than 80oC. The media that the induced-draft professional fan transmitted is gas; the highest temperature of the gas should be less than 250oC. A dust-clear system should be installed in front of the induced-draft fan in order to decrease the dust and improve the service of its life