Why are duct leak tests required?

10-30% of heated/cooled air is lost through ductwork. Supply ducts with leaks will not deliver air where needed. Leaking return air ducts add load to the equipment. Leaky air ducts can draw air from unconditioned spaces and thereby adversely affect the cooling /heating and humidity control of the building, it also draw contaminants from the un conditioned areas and affect the indoor air quality.

Various standards for duct leak test

USA

• smacna hvac air duct leakage test manual, first edition, 1985
• ashrae 90.1 (proposed)

Note: ashrae 90.1 recommends only testing ductwork rated >3 inches h2o

 EUROPE

• bs en 12237:2003 12237:2003 – circular ductwork circular ductwork
• bs en 1507:2006 – rectangular ductwork
• dw/143 (hvac—a practical guide to ductwork leakage testing)
• eurovent 2/2 (air leakage rate in sheet metal air distribution systems)