Feb 06

Ductwork Makes Banging Noise: Causes & Solutions

image of homeowner covering ears due to ductwork noise

Central heating and AC systems generate warm and cold air distributed throughout the house through a network of ducts. The ductwork is typically made of metal, so they are prone to making noises at the slightest disturbance. It may become annoying if the sounds are loud and frequent. It may even keep you up at night. This article discusses why ductwork noise happens and how you can reduce it.

Explore Our Heating & Cooling Services Call To Schedule A Free, In-Home Estimate

Possible Reasons Behind Ductwork Noise

HVAC ducts may emit noises for various reasons. Listen closely to determine the kind of sound it is producing. Although you may not see the reason for the issue, you can get an idea from the sounds you hear. One of the most common HVAC ductwork noises we deal with is a banging sound.

Ductwork Is Banging

Several homeowners report hearing noises similar to banging and popping inside the ducts. The sound usually happens in short bursts. It occurs because the ductwork walls expand and contract during changes in internal temperatures. Another reason for this noise is pressure fluctuations. Keep in mind that cold air makes ducts contract while the hot air makes them expand. Our human eyes may not see these happen, but you can hear them as it happens after switching on your air conditioner or furnace.

Call Today: (908) 707-1776

Causes For Additional Ductwork Noises

The ducts can also emit different sounds aside from banging and popping. Here are four common noises and why they happen:

Rattling Ductwork

hvac air ducts

Loose metal parts are the likely culprits of rattling noises from inside the ducts. These loose parts knock against one another, which tends to occur as the ducts age. Static pressure causes the seals to start failing and the connections to become loose. The sound will be heard as long as air flows through the ductwork. You may start hearing a soft sound, but it will get louder as time passes until it can’t be ignored any longer. Have an HVAC professional help in finding and repairing the problem.

Booming HVAC Ductwork

You may hear a loud boom at the joint of the ductwork’s trunk and the plenum. This area encounters the biggest temperature swing. If this junction has insufficient expansion joints or dampers, the noise will reverberate throughout the house via the supply ducts. Skilled and experienced installers know this can happen. Therefore, they do all they can to reduce the noise from this connection.

Learn More About Our HVAC Services Call To Schedule A Free Estimate

HVAC Ductwork Is Shaking

You may hear your ducts vibrating with a low hum or see the ducts shaking. This usually happens when there’s a blockage on the return side’s airflow due to a dirty filter. The pressure drops because air cannot enter, causing an extreme pressure drop that makes the duct walls shake and vibrate. Habitually check the air filters. Clean or change them if they start getting too dirty. Doing so helps the system maintain high efficiency, and the ducts will operate more quietly.

Scratching Ductwork

Another unwelcome sound from the ductwork is scratching noises. If you hear something scratching the metal walls, it is likely that creatures like squirrels, rats, and raccoons have entered your system. Do something about it right away, or the animals may create a nest and make your system their home. This will negatively impact your indoor air quality. If it’s a buzzing noise you hear, it may be because of the wings of a bee or giant insects trapped inside. Contact your local, trusted HVAC technician to assist you.

How to Reduce HVAC Ductwork Noise

Homeowners don’t have to endure the noise. You can remove foreign objects, small animals, and insects from the ducts. Competent HVAC contractors can fix problem areas. You can also reduce the loudness of the noise from the system’s normal operations, so it becomes bearable for homeowners who want a quiet home. Here are some solutions you can do to help this:

Adjust The Fan Speed

heat pump fan

HVAC installers determine the airflow volume at the outset. Each system has its own optimum range, which can be determined after accounting for several factors. The airflow volume is frequently set at a too-high speed. If this is happening in your home, lower the fan speed to reduce the static pressure. Consult an HVAC technician, as setting the fan speed too low can make it hard for conditioned air to get to certain rooms.

Call To Schedule An Appointment

Replace The Air Filters To Avoid HVAC Ductwork Noise

Be watchful of your filters. They trap the dirt while letting air pass through. The more dirt they catch, the harder it becomes for air to pass through the barrier. These require replacing every two to three months, so there is good airflow and efficiency. However, homes with pets and houses located in dusty areas may need to replace their air filters once a month. How often you need to change the filters depends on your unique home situation. A clean filter keeps the banging and popping sounds from the ducts. Air filters are relatively inexpensive, so replace them immediately and help your HVAC system run better.

Install Larger Ducts

image of an hvac contractor with hvac ducts

Consider the likelihood that you have too-small ducts for the air volume that the system requires to run well. Your HVAC units may be correctly sized, but undersized ducts will still cause issues. Call an HVAC contractor to assist you in studying the matter. Larger ducts and return and supply plenum help in reducing the noise. Use these along with high-velocity grills and registers for better airflow.

Add a Bypass Duct To Avoid Ductwork Noise

Utilize a bypass duct to lower the pressure in a multi-zone system. Reducing the pressure is an excellent method to get rid of excess stress on the duct and prevent common problems. However, this is only effective in certain cases. Talk to HVAC professionals to see if this option suits your ducts.

Try a Different Duct Shape

Consider the shape if you are installing new ducts. Rectangular ducts are popular due to their clean lines and slim profile. However, they are more likely to generate more noise than round ducts due to lower pressure tolerance. It may be worth looking into round ducts if they can fit in your home. Consult a local HVAC company for professional assistance.

Get Started - Call Skylands Energy Service Today Explore Our Case Studies

Use a Duct Silencer

Duct mufflers can be installed in round ducts to further reduce the noise they generate. This component is designed with a double wall and insulation to dampen vibrations. Mufflers work best when placed close to components that make the most noise, like the air handling unit and fan. Keep in mind that these only reduce unwanted sounds and do not entirely eliminate them.


Insulate the Ducts

Insulation can be wrapped around ducts to enhance their energy efficiency. This also helps reduce noise, especially popping and banging noises. Hire a certified technician to do this for you to ensure you get the best results.

Switch to a Ductless System

ductless hvac system

If you are still unsatisfied even after doing these noise reduction strategies, you should consider completely moving away from ducts. Consider switching to a ductless mini-split instead, as they don’t have ductwork, so there’s no noise, and no duct maintenance is needed. Ductless units also come with perks like creating multi-zones, higher energy efficiency, and independent temperature control.

Get Started - Call Skylands Energy Service Today



Noise in your ducts can point to several reasons. An underlying issue like loose connections, incorrect system configuration, and pest infestation may sometimes cause it. The noise, in these cases, alerts homeowners that the system has a problem that requires attention. However, the sound could also be due to the system’s regular operations. It may not go away, but you can conduct different methods to reduce the frequency and loudness. Discuss it with your HVAC contractor to find out which are the best solutions for your system.

Call Skylands Energy Service For All Of Your HVAC Requirements

image of skylands energy service logoTo ensure you receive superior HVAC services in central New Jersey, contact Skylands Energy Service. We have the best professionally certified technicians to help you with your heating and cooling needs, like AC tune-ups, boiler repairs, ductless mini-split installations, and furnace replacements. Each of our HVAC technicians is skilled, experienced, and knowledgeable to service any HVAC system correctly and on time.

Rest assured, we offer highly affordable HVAC service prices. Our maintenance services can enhance the home’s energy efficiency, comfort, indoor air quality, and more while lowering energy costs. If you need an HVAC repair or replacement system, we can recommend the most suitable and budget-friendly one for your home. We back all our work with a guarantee because we want to ensure your satisfaction. Book a service appointment today with Skylands Energy Service. Call us now and receive a free, in-home estimate.

Call Now: (908) 707-1776 Read Our Reviews

Contact us now at (908) 707-1776 to find out more! Click the link to view our service area.

Don`t copy text!