ARLINGTON, Va. - The Air Conditioning Contractors of America (ACCA) released a revised and improved version of “Manual D - Residential Duct Systems.” According to ACCA, this book is the association’s most bestselling technical manual and the industry standard for residential HVAC duct design.

The new version of “Manual D” maintains the popular and accurate procedure of the classic manual, but has been enhanced with a number of new improvements, including: new equivalent length values for flex duct junction boxes; updated guidance, with examples, for variable air volume (VAV); and impacts of excess length, sag, and compression in flexible ducts.

Authored by Hank Rutkowski with the oversight of a committee comprised of professionals from different sectors of the HVACR industry, the updated “Manual D” was approved as the national standard for residential duct design by the American National Standards Institute (ANSI) on Jan. 22, 2009. The Manual D principles and calculations can be applied to constant volume systems and zoned variable air volume systems, over a full range of modern construction materials.

According to David Hutchins, chairman of the ACCA Technical Services Committee and president of Bay Area Air Conditioning in Florida, “The new information about proper flex duct design alone makes this new edition of Manual D a must-have.”

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Publication date:02/23/2009