Duct cleaning and duct sealing get lumped together often, sometimes even marketed as a single service, but they address genuinely different problems. Knowing which one actually matches what you're dealing with helps you avoid paying for the wrong service.
What duct cleaning addresses
Duct cleaning removes accumulated dust, debris, and in some cases mold or pest contamination from inside the ductwork itself. It's primarily an indoor air quality service, addressing what's actually circulating through the air you breathe, rather than a fix for airflow, comfort, or energy efficiency problems.
What duct sealing addresses
Duct sealing addresses physical leaks and gaps in the ductwork itself, at joints, seams, and connections, where conditioned air is escaping before it reaches your rooms, or where unconditioned attic or crawlspace air is being pulled in. This directly affects comfort, energy bills, and how hard your system has to work to maintain temperature, since leaking ducts mean you're paying to cool or heat air that never actually makes it into your living space.
Signs that point toward duct sealing
Noticeably higher energy bills without an obvious cause, rooms far from the furnace or AC that never feel as comfortable as rooms closer by, and visible gaps or disconnected sections in accessible ductwork (in an attic or crawlspace) all point toward a sealing issue rather than a cleaning one.
Signs that point toward duct cleaning
Visible dust buildup at vent covers, a musty smell specifically when the system first turns on, or a home that's had recent renovation work (which kicks up a lot of dust into the duct system) are more indicative of a cleaning need than a sealing one.
Can you need both?
Yes, and it's common in older homes that haven't had either service done in years. A proper inspection identifies whether leaks, contamination, or both are present, rather than assuming one service solves a problem it wasn't actually designed to address.
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