Troubleshooting & Fixing HVAC Ductwork Noise

Central heating and air conditioning systems generate warm or cold air in a central location and then circulate it through the house using ducts. These ducts, typically constructed from metal, are prone to producing ductwork noise with even minor disruptions. Such noise can irritate homeowners, mainly if it’s loud and persistent, potentially disrupting a good night’s sleep. Continue reading this article from Modern Comfort to discover the reasons behind this issue and explore strategies for minimizing them.

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Possible Causes of HVAC Ductwork Noise

homeowner writing down cause on notepad depicting ductwork noise causes

Several factors can cause your HVAC ducts to be noisy. By paying attention to the specific types of sounds produced, you can gain insights into the underlying issues, even without visual confirmation. A banging noise from the HVAC ductwork is notably common.

Banging Ductwork Noise

Many homeowners have noted popping and banging sounds from their ducts in quick, intermittent bursts. These noises are typically caused by the ductwork’s walls expanding and contracting with internal temperature shifts. Changes in pressure within the ducts may also prompt these sounds.    The expansion happens with warm air, while contraction occurs with cool air. Although these changes might not be visible, they are audible soon after the heating or cooling system is activated.

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Identifying Other Common Ductwork Noises

Beyond popping and banging, ductwork can emit various other sounds, each with its own set of causes.

Rattling Sounds in Ductwork

man inspecting home air vent due to rattling ductwork noise

Rattling noises from your air ducts often indicate that loose metal parts are the culprits. These parts can produce noise as they collide, becoming more common as ductwork ages. Over time, seals may weaken, and connections can loosen due to constant static pressure. This rattling sound persists as air circulates through the ducts, starting as a mild noise and gradually becoming louder until it demands attention. Addressing this issue promptly with the help of HVAC professionals is crucial to finding and remedying the cause.

Addressing Booming Sounds in HVAC Ductwork

A booming sound emanating from your HVAC ductwork, especially noticeable at the connection between the duct’s trunk and the plenum, signals significant temperature fluctuations at this juncture. If this area lacks sufficient expansion joints or dampers, the booming noise can travel throughout the home via the supply ducts. Experienced installers know this possible issue and take preventive measures to mitigate noise from this connection.

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Shaking in HVAC Ductwork

Noticing your ducts shaking or vibrating, accompanied by a low hum, can often be attributed to a blocked airflow on the return side due to a dirty filter. This blockage lowers the pressure enough to cause the duct walls to vibrate. Regularly monitoring and maintaining your air filters is vital. When a filter becomes too dirty, cleaning or replacing it will help quiet the ducts and ensure your system remains efficient.

Scratching Sounds in Ductwork

cat scratching a post depicting scratching ductwork noise

Scratching noises within air ducts often suggest the presence of unwelcome guests, such as rats, raccoons, squirrels, or other animals that have found their way into the system. Immediate action is crucial to prevent these creatures from nesting and deteriorating the air quality in your home. A buzzing sound could also indicate giant insects, like bees, trapped inside the ducts. Reach out to an HVAC professional for assistance.

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Strategies for Minimizing HVAC Ductwork Noise

Homeowners can effectively tackle noise issues in their HVAC ductwork. This includes removing animals and debris and fixing defects by professional HVAC technicians. Several actionable steps exist to decrease volume and enhance home tranquility for noises stemming from the system’s normal function. Below, we outline essential strategies to achieve quieter ductwork:

Regular Air Filter Replacement

homeowner replacing filter in hvac system

Regularly check your air filters, which are crucial for trapping dirt and maintaining airflow. As filters fill, they can restrict airflow, so replacing them every 2-3 months is vital for maintaining efficiency and performance. Homes with pets or in dustier locations may require more frequent, monthly replacements. Timely filter changes are an affordable and straightforward maintenance step that boosts system efficiency and minimizes everyday duct noises, such as banging and popping, keeping your HVAC system running smoothly.

Modulating Fan Speed

The HVAC system’s airflow volume is set based on a calculated optimal range, considering various factors. Sometimes, this initial setup results in a fan speed that’s higher than necessary, leading to excess noise. Lowering the fan speed can be a solution to reduce this noise by decreasing static pressure. However, adjusting the fan speed is a precise task, as setting it too low might impede the distribution of conditioned air to some areas of your home. Consulting with an HVAC professional is recommended for accurate adjustments.

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Upgrade to Larger Ducts

HVAC technician installing bigger ducts for the client

If your HVAC system is noisily straining, the issue might be that your ducts are too small for the required air volume. Even if your heating and cooling units are properly sized, undersized ducts can lead to inefficiency and noise. Consult with your HVAC contractor for an assessment. Upgrading to larger ducts and expanding the return and supply plenum can significantly reduce noise levels. Incorporating high-velocity grills and registers further enhances airflow.

Say goodbye to noisy ductwork by upgrading to properly sized ducts. Contact Modern Comfort to assess your system today. Call now!

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Incorporate a Bypass Duct 

High pressure can strain ductwork in multi-zone HVAC systems, leading to issues. Installing a bypass duct can alleviate this pressure, enhance system longevity, and prevent problems. This solution isn’t universally applicable, so consulting with HVAC professionals is crucial to determine if it’s suitable for your system.

Selecting a Different Duct Shape

man choosing for a different shaped ductwork to minimize noise

For new duct installations, shape significantly influences noise levels. While rectangular ducts are preferred for their aesthetics and space efficiency, they can be noisier due to lower pressure tolerance. Round ducts, offering quieter operation, might be a better option if compatible with your home’s layout. Consult a local HVAC company to determine the best choice for your needs.

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Install a Duct Silencer

Consider installing a duct muffler to minimize noise in round duct systems. These devices effectively dampen vibrations and feature a double-wall construction and internal insulation. Install them close to the air handling unit, fan, or other noisy components for optimal noise reduction. While duct silencers significantly reduce unwanted sounds, it’s important to note they don’t completely eliminate noise.

Consider a Ductless System

Ductless Cooling

If you’ve implemented various noise reduction techniques yet still face dissatisfaction with the noise level, transitioning to a ductless system could be the solution. Ductless mini-split systems eliminate ductwork noise and maintenance concerns, offering additional benefits such as zoned temperature control, independent operation in different areas, and improved energy efficiency.

Are you tired of ductwork noise? Transition to a ductless system for silent operation and enhanced comfort. Call Modern Comfort today to learn more!

Install Duct Insulation

Wrapping your ductwork in insulation boosts its energy efficiency and helps muffle noises, particularly the common banging and popping sounds. Have a certified technician install this insulation for optimal effectiveness and safety.


Ductwork noise can signal various issues, from pest infestations and improper system setups to loose fittings, as an early warning for homeowners to address potential problems. While some noise may be inherent to the system’s operation, it doesn’t have to be disruptive. Several strategies exist to lessen the intensity and occurrence of such noises. Consulting with an HVAC professional can help identify the most effective solutions tailored to your system’s needs.

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Modern Comfort is your go-to source for top-tier heating and cooling solutions in Central Maryland and Southern and Central Pennsylvania. Our highly qualified technicians, each professionally certified and equipped with extensive expertise, can perform superior HVAC tune-ups, repairs, installations, and replacements. We are proud to offer the most affordable pricing on heating and cooling services.

Opting for our maintenance services can enhance your comfort, boost your system’s energy efficiency, and lower your heating and cooling expenses. Should you require HVAC repair or are considering a new system, Modern Comfort is here to assist you with the best options that fit your needs and budget.

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