HVAC Noise Reduction: How to Control & Reduce HVAC Noise

Noisy HVAC systems can be a problem for both residential and commercial systems. To keep buildings comfortable year round, these systems must pump large volumes of conditioned air continuously throughout the building. Unfortunately, moving these volumes of air often generates unwanted noise in the process.

While no one enjoys listening to a noisy HVAC system, there are fixes you can do to keep your home or building comfortable and your HVAC system quiet.

Where Does HVAC Noise Come From?

HVAC systems have hard jobs. Keeping occupants comfortable means moving and conditioning large volumes of air and being quiet while they do that. Noisy HVAC systems reduce comfort, productivity, and overall system efficiency. Noisy systems should be addressed but where do these noises come from? Some of the most common sources of HVAC noise come from:

Airflow through ducts

Movement can lead to noise and air flow is no exception. The speed of air traveling through ductwork can generate unwanted noise in the process, especially if ductwork is able to rattle. Sharp bends in ductwork can also cause increased noise as the air flows through these sections and causes turbulence.

Fans, compressors, and motors

Components in an HVAC system can all contribute to the overall noise. Compressors, fans, and motors are all pieces of equipment that move when the system is energized. These components can introduce vibrations or imbalances that result in noise. Airflow picks up these squeaks and vibrations resulting in both conditioned air and noise getting delivered to rooms.

Air leaks

In addition to ductwork causing rattles and vibrations, leaky ductwork can be a big contributor to noise. Leaks in ductwork not only waste energy but can cause whistling sounds or other noise as air escapes through these leaks.

Undersized Ductwork

While it may seem like just simple sheet metal, HVAC system ductwork is carefully sized to meet the needs of the overall HVAC system. When return vents or ductwork are undersized, meaning more air is being pulled or pushed through the ductwork than the recommended amount, excessive noise is generated in the process.

So How Do We Fix the Noise?

Understanding where HVAC noise comes from is a great first step, but solving the noise problem is what you are really after. Identifying the noise source is always the best place to start. Once you’ve identified the issues, you can apply some of the fixes below to keep your HVAC system efficient and quiet.

Sealing Air Leaks

One of the easiest fixes to perform is sealing up leaks. A roll of foil tape can make this job a breeze. A smoke pencil or other device can help you find stubborn leaks. Patching these leaks will make your HVAC system quieter, more efficient, and reduces the likelihood of mold or condensation issues from developing later on.

Reducing Duct Rattle

If you’ve identified that your HVAC noise is coming from your ductwork rattling, you have a few options. If the pressure in the ductwork is causing your noise, stiffening the ductwork to prevent movement is an option. Ensure that the ductwork is properly supported and add vibration dampening components where needed. Use flexible ducts where it makes sense to alleviate some of the stress caused by hard duct connections.

Reduce Inlet Noise

When systems draw in outdoor air as part of their operation, it can be important to strip that noise out before it enters the rest of the system. Acoustical louvers do just that. The blades of these louvers are designed to reduce and dissipate noise in air as the air passes through the damper.

Upgrading Your HVAC System

When components like a system’s compressor are causing large amounts of noise, it may make sense to consider replacing the system with a newer, more efficient, HVAC system. Modern systems use less energy and generate less noise than their older counterparts. For old systems, this can make more sense than spending money to try to solve the problem in other ways.

Balancing Air Flow

Getting airflow volumes just right is key to delivering the appropriate amount of air for the system. Too much airflow can easily cause excess noise. Volume dampers are key to getting the air volumes dialed in for each branch of ductwork. For specific applications, custom dampers can be the right choice to ensure the HVAC system can operate as designed.

Compressor Blankets

Equipment like compressors have hard jobs that naturally generate a good bit of noise. The use of soundproof blankets to wrap around the compressor and absorb noise dissipates the sound right at the source. These blankets prevent the noise from traveling into the system making the whole HVAC system operate with less noise.

Vibration Control

Just like compressors, blower motors can generate a lot of noise during their operation. Because of their high speed operation, these components can cause vibrations to travel to unwanted parts of the HVAC system. Installing vibration isolators or pads to prevent these vibrations from traveling prevents a lot of unwanted noise at the same time.

Quieter HVAC Systems Through Design

While many of the earlier options will work on reducing noise in existing installations, proper design can help prevent a lot of noisy issues in the first place. System components that produce noise, like condensing units, should be placed away from bedrooms and quiet areas. Sufficient space around these units will allow for proper airflow and reduced noise. Sound barriers around ducts can be a great way to get ahead of issues as well. These can be especially important for bedrooms, offices, and living areas.

Commercial installations with mechanical rooms can greatly benefit from strong design practices. Many times, ventilation for these areas can be designed as a sound maze to both limit sound transfer and absorb as much generated sound as possible. Louvers can be designed and placed to ventilate these rooms in a fashion where noise will be reduced, especially when coupled with acoustic dampening materials.

Reduce HVAC Noise with United Enertech

Finding sources of HVAC noise and stopping them at the source is always the first line of defense for noisy HVAC systems. Keeping occupied spaces free from HVAC noise makes them more comfortable and productive for the occupants. When additional components are needed to tackle tough environments, United Enertech’s suite of products are up for the challenge.

To learn more about how our products reduce HVAC noise, reach out to our team of experts today.