Duct leakage is one of the most common and costly issues in both residential and commercial HVAC systems. It occurs when conditioned air escapes through gaps, seams, or disconnected sections of ductwork before reaching its intended space. This not only reduces system efficiency but can also lead to comfort issues, poor indoor air quality, and failed energy code compliance.

What Is Duct Leakage Testing?

Duct leakage testing is a diagnostic procedure used to measure the airtightness of a duct system. Using specialized equipment such as a duct blaster fan and digital manometer, the system is pressurized or depressurized to quantify air loss, typically reported in CFM (cubic feet per minute) at a specified test pressure (commonly 25 Pascals).

This test is a critical component of energy code compliance, particularly under the International Energy Conservation Code (IECC), which sets maximum allowable leakage thresholds for both residential and commercial buildings.