Initially developed 30 years ago for packaged boiler systems, Chicago's Packaged Forced Draft fan has earned a reputation as the industry standard. The PFD is a compact, direct connected, airfoil bladed fan offering exceptional reliability. To afford the highest efficiencies throughout the performance range, there are three wheel diameters available for each fan size. Fan and wheel width can also be varied to obtain maximum performance. For systems design versatility, seven standard discharge positions can be specified in each rotation.