The McQuay Duct Sizer relies on the Darcy-Weisbach equation adapted for air: [ h_f = f \cdot \fracLD \cdot \fracV^22g ] Where:
Use the McQuay/Daikin Duct Sizer as a pre-design tool, then validate with a full duct network analysis (e.g., in Revit or Elite DuctSize) before procurement.