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December 23, 2020

Ductwork Making Banging Noise: Common Causes

ductwork making banging noise

Air ducts are one of those necessities we like to keep out of sight and out of mind, but what happens when they make noise? In this post, we’ll take a look at common causes for ductwork making banging noise.

Fortunately, most noises coming from ductwork aren’t a cause for major concern. Common sounds you might hear include banging, popping or booming sounds.

Common Causes for Air Duct Noise

Noise in ductwork often occurs right after an HVAC system kicks on and air begins to circulate. The sudden airflow leads to a change in air pressure inside the ductwork. As a result, the thin metal sheets they’re made of expands, likely causing those banging, popping noises. It’s possible you might notice these sounds, or notice them more frequently, after ductwork has been cleaned, or after an HVAC unit has been serviced. Both instances are likely to create more efficient airflow, which means greater changes in air pressure.

Differences in Ductwork

The shape, size and thickness of ductwork can all impact the amount of noise they generate. Air ducts installed in homes are often made of thin sheet metal, which is inherently more prone to noise as it expands. The shape of ductwork also comes into play—round air ducts handle changes in air pressure best of all, followed by square ducts and finally rectangular ducts.

When ductwork noise becomes too much of an inconvenience, consider making changes to the shape or material of your air ducts.

Other Causes for Air Duct Noise

Other potential causes for banging or popping sounds include:

  • Dirt or debris build-up inside of ductwork.
  • Ductwork that is too small for the HVAC system.
  • Ductwork hangers and supports might make noise as ductwork expands. Try insulating air ducts at these points to reduce contact noise.


While occasional pops and banging noises in air ducts are a normal part of operation, if you notice new, strange noises, or if the noises increase without corresponding to a recent cleaning, have a professional take a look. Your system might need a thorough cleaning or worn/broken parts might need to be replaced. If the level and frequency of noise is an inconvenience, an HVAC professional can evaluate your ductwork and make suggestions to help decrease air duct noise.

Gold Star Services has a team of highly skilled HVAC technicians ready to help! Our services include heating, cooling and water heater repair, replacement and maintenance. Call 1-302-947-8694 to connect with Gold Star Services today!

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