The American Society of Heating, Refrigerating and Air-Conditioning Engineers and the Air Distribution Institute have created a new duct-sizing calculator for air-distribution system designers.

The new calculator offers increased accuracy for sizing ducts, especially flex ducts under varying amounts of compression, according to research results from the organizations. The calculator relies on information from ASHRAE research project No. 1333 — aka HVAC duct-efficiency measures — and includes fields for 4, 15 and 30 percent compression in flexible ducts.

“While the calculator resembles a wheel-type ‘ductulator’ similar to those used during the days of slide rules, it incorporates three new fields for equivalent duct sizing,” said Chris Van Rite, who developed the calculator. “These new fields help demonstrate the significant loss of airflow due to improper installation of flexible ducts.”

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