Matt, how can airflow measurements be used to diagnose duct leakage or restrictions?

In this edition of “HVAC Skill Builder,” Matt discusses diagnosing duct leakage or restrictions with airflow measurement.

Matt, how can airflow measurements be used to diagnose duct leakage or restrictions? When it comes to duct restrictions, airflow measurements, namely static pressure, can be used. And one of my most common diagnostic techniques was if you have a system that has a zone motor in it, and what I used to do was check the pressure going across the zone motor, and I would turn it on, and if I had a pressure drop when it called, then I would know that zone motor is opening and closing. And if I did not have a pressure drop, that would tell me that that zone motor is either not opening or closing, and I would have to do further diagnostics to determine what’s causing that issue.