You’ll learn what total external static pressure actually tells you (and what it doesn’t), where to place your manometer probes on a furnace or air handler, and why exceeding the manufacturer’s rated pressure limit means you’ve got a problem to solve. Ty also breaks down the relationship between filter size, surface area, and pressure drop — including why that oversized filter box you thought looked weird might actually be the right call. He covers coil placement, transitions, probe placement considerations around diverter plates and drain pans, and how to think about external restrictions on both the supply and return sides.

The key takeaway: TESP is like reading your blood pressure — critical data, but it doesn’t tell you actual airflow. Understanding how to test and interpret it properly is what separates a real diagnosis from a guess.

Whether you’re working on gas furnaces in the field or trying to get better at air handler diagnostics, this one’s worth your time.