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The newly revised fourth edition of the “HVAC Systems Duct Design” manual presents the basic methods and procedures required to design HVAC air distribution systems. This manual provides the HVAC system designer detailed information on duct design. Both IP and SI units are provided in all examples, calculations, and tables.

In addition to the basic engineering guidelines for the sizing of HVAC ductwork systems, the manual also provides related information on materials, methods of construction, economics of duct systems, duct system layout, pressure losses, fan selection, duct leakage, acoustic considerations, and Testing, Adjusting and Balancing (TAB).

With the current industry emphasis on energy conservation, the designer must balance duct size with the building space required and duct system pressure loss. Duct pressure and frictional losses increases fan power and associated HVAC system operating costs. Materials, equipment, and construction methods must be carefully chosen for both initial cost and life-cycle costing considerations.
The SMACNA “HVAC Systems Duct Design” manual was written to be used with ASHRAE’s Handbooks. The basic fluid flow equations are not included in the new publication, but may be found in the ASHRAE Handbooks. Practical applications of these equations are included through use of reference tables and examples

Although most commercial HVAC systems are constructed to pressure classifications between minus 3 inches wg to 10 inches wg, (-750 Pa to 2,500 Pa), the design methods, tables, charts, and equations provided in this text may be used to design other duct systems operating at other pressures and temperatures. Air density correction factors for both higher altitudes and temperatures are included.

This manual is part of a SMACNA three-set HVAC systems design library. The second publication is the SMACNA “HVAC Systems-Applications” manual that contains information and data needed by designers of more specialized air and hydronic HVAC systems. The third book is the “HVAC Systems-Testing, Adjusting and Balancing” manual, a recently updated publication on air and hydronic system testing and balancing.