Mike PleziaInside service technician, Clark Associates · Commercial Equipment, HVAC, and Refrigeration professional

Duct Leakage: The Air You're Paying For

10 Oct 2026 · 1 min

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1:04

In this instructional monologue aimed at new HVAC tradespeople, the speaker explains how duct leakage—both supply and return—causes conditioned air to be lost to unconditioned spaces such as attics, crawl spaces, and garages. This loss forces the HVAC system to run longer, raising the customer's energy bill and reducing comfort. Supply leaks waste conditioned air before it reaches living spaces, while return leaks draw hot, humid air in summer or cold air in winter, making the equipment work harder. The speaker then provides practical inspection guidance: examine duct connections, feel for air movement at joints and seams, and watch for common issues like torn flex duct, disconnected trunk lines, and missing ductboard. By identifying these problems early, technicians can prevent customer complaints about high utility costs.

Chapters

Hey, are you new to the trades? Here's something you may not know about duct leakage and what it costs a system. When supply ducts leak into an unconditioned space— an attic, a crawl space, a garage— you're paying to condition air that never reaches the living space. The system runs longer. The customer pays more. Comfort suffers. And when return ducts leak, they pull in unconditioned air from those same spaces. In summer, that means hot, humid air entering the system. In winter, cold air. Either way, the equipment is working harder than it should. On every call, look at the duct connections. Feel for air movement near joints and seams. Torn flex duct, disconnected trunk lines, and missing ductboard are more common than you'd think, and they're often hiding in plain sight. Leaky ducts are a problem you can find before the customer asks why their bill is so high. Now that you know, you can help someone else know.