Eliminate Noisy Air Vents in Your Facility – Sobieski Services | DE, NJ, PA, MD

Eliminate Noisy Air Vents in Your Facility

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When everything is operating normally in your commercial building’s HVAC system, there should be very few noises coming from the air vents. The most common noise is the sound of air moving through the ductwork, or the sound made by fans and other components as they turn off and on. If you, your staff, or your tenants have noticed other noises in the air vents, such as louder sounds or unfamiliar noises, there could be a problem somewhere in the system. Here is some background information on the most common types of noisy air vents, along with details on what causes the noise and what can be done to stop it.


Your HVAC system is designed to keep up a steady circulation of air. Supply ductwork and vents send heated or cooled air out and into the interior of your building. Return registers and ductwork pull expended air back into the system to be filtered, reconditioned, and sent out again. This means that there is a lot of ductwork where noise problems could develop. It also means that finding and resolving problems with noisy air vents requires a careful check of both supply and return systems.

Common Sources of Noisy Air Vents

  • Restricted airflow: Restricted airflow is a common source of noisy air vents and unusual sounds in an HVAC system. A heating or cooling system with plenty of air returns will usually operate much more quietly than one with only the minimum number of returns required for operation. If airflow restriction occurs, it can produce a high-pitched humming or vibrating type of sound. Restrictions can happen if there are objects blocking a return register, if the ductwork is too small, or if the air filter is clogged and not allowing air to flow through it. Changing air filters or removing whatever is blocking the register are simple solutions, while installing larger ductwork could be costly.
  • Loose ductwork or system components: Over time, ductwork sections can come loose, as can components of the HVAC system. It is also possible that an access door has been left unfastened. These issues could produce rattling, knocking, or clanging sounds as these loose components knock against each other. If the ductwork is loose or has developed leaks, it could produce hissing, roaring, or whistling-type sounds as the air moving through the ductwork escapes through the leak. Reconnecting and resealing loose ductwork sections, tightening system components, and securing access doors are common and relatively simple ways to solve this problem with noisy air vents.
  • Objects in ductwork: Supply vents and return air grilles in commercial buildings are usually installed to prevent objects from falling into them. If your building has floor vents, however, it is very possible that small items could fall into the vent system. Screws connecting duct sections could also fall out and into the ductwork at almost any point in the system. These items could generate rattling, tapping, or knocking sounds. A professional duct cleaning is a good solution to this problem. The type of ductwork inspection that is part of seasonal maintenance should also be thorough enough to find and remove any objects or debris in the ducts.
  • Expanding or contracting ductwork: As heated and cooled air moves through the ductwork, the metal of the ducts will expand or contract. The sound of this movement of the ducts could create noisy air vents and produce unfamiliar sounds. Expanding or contracting ductwork can produce clicking, ticking, or cracking types of sounds. In general, these types of sounds are perfectly normal, but they could be reduced by thoroughly insulating the ductwork.

Our goal is to help educate our customers about Plumbing, HVACR, Fire Protection, and Alarm Systems in Mechanical, Commercial, and Residential settings. For more information on identifying and resolving problems with noisy air vents, or to view projects we’ve worked on, visit our website!

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