Self-Generated Noise: Here’s What It Is and How to Stop It

A critical but often overlooked aspect of HVAC systems is the concept of self-generated noise. It is inherent in the operation of HVAC systems and significantly affects the comfort and efficiency of indoor environments. Not all self-generated noise is created equal and the impacts can vary. Once self-generated noise is uncovered, the proper effective management strategy can be implemented both to correct the noise problem, and to fix any issues with the system highlighted by the noise.

Self-Generated Noise: Here’s What it is and How to Stop it

Types of Self-Generated Noise in HVAC Systems

Self-generated noise in HVAC systems arises from various elements of the system’s operation. Noise is often caused by inefficiencies associated with motion. HVAC systems have fast moving parts and move large volumes of air significant distances. It creates a lot of opportunities for noise to be generated.

Air movement noise

The most prevalent source of self-generated noise is air movement noise, which occurs when air flows through ducts and vents and creates turbulence, especially at high velocities. This can result in a range of sounds, from gentle whooshing to loud rumbling, depending on the system design and air speed. The high velocities also increase pressure drop in the HVAC system, which puts more strain on the blower motor.

Mechanical Operations

Another key source of noise is the mechanical operation of components like fans and compressors. They are essential to the functioning of the HVAC system, and they can produce varying levels of noise depending on their condition and design. An imbalance in these components, or wear and tear over time, can lead to increased noise levels that signal potential maintenance needs.

Vibration-induced Noise

Vibration-induced noise is another significant factor. The vibrations from the HVAC equipment, if not properly isolated, can transmit through the building's structure and create a background hum or rattling sounds. This type of noise is not only bothersome, it can also indicate deeper structural issues.

Regenerated Noise

Regenerated noise occurs when noise from one part of the system, such as a noisy fan, is carried through the airstream and emitted elsewhere, often far from the original source. This can be particularly challenging to diagnose and rectify in large HVAC systems.

The Importance of Managing Self-Generated Noise

The impact of unmanaged self-generated noise is manifold. In residential environments, excessive noise can disrupt comfort and sleep and detract from the quality of living. In commercial and office settings, noise pollution can reduce productivity and concentration which impacts the overall work environment. Meeting building codes and noise regulations is also a key consideration, particularly in densely populated areas

Excessive noise often points to inefficiencies in the HVAC system. While bothersome, noise can be an early warning sign of problems that can lead to increased energy consumption and reduced system longevity.

Paying attention to these types of signs and investigating to learn their causes can reap benefits and extend system life cycles.

Residential and Commercial Self-Generated Noise Troubleshooting Examples



Consider a residential scenario where a loud whooshing sound emanates from the air vents. This issue often stems from high air velocity or a duct layout that creates excessive turbulence. Addressing this issue might involve reducing the fan speed or redesigning the ductwork for smoother air flow or lower duct velocities.


In a commercial setting, a common issue is the vibrating noise from an HVAC system that is frequently due to an unbalanced fan. Regular maintenance, including precise balancing and alignment or bearing replacement, can effectively resolve this issue.

Large Commercial

For large commercial buildings, regenerated noise can be a complex challenge. Sound from equipment rooms may travel through ducts into office spaces. Employing sound-attenuating materials within the ductwork can significantly reduce this type of noise transmission.

Best Practices for Noise Reduction in HVAC Design and Maintenance

Effective noise reduction in HVAC systems begins at the design stage. Selecting equipment with low noise levels, ensuring proper installation, and designing ductwork to minimize turbulence and air speed are crucial steps. Design guidelines exist for a reason, and adhering to them helps ensure a suitable end design. Incorporating sound-attenuating materials and vibration isolators can also greatly mitigate noise issues.

Regular maintenance is equally important. This includes routine checks and balancing of components, cleaning to prevent obstructions that can cause noise, and timely replacement of worn parts. Noise arises from inefficiencies that can lead to premature failures. Proactive maintenance not only reduces noise, it also enhances the overall efficiency and longevity of the HVAC system.

Noise Isn't Necessary: Resolve Self-Generated Noise with Metal Form Manufacturing

Recognizing and addressing self-generated noise in HVAC systems is essential for creating a comfortable, efficient, and productive indoor environment. By understanding the various sources of noise and implementing best practices in system design and maintenance, one can significantly improve the performance and lifespan of these essential systems.

Adhering to proper design guidelines and engaging in preventative maintenance minimizes self-generated noise and extends system longevity. Sound attenuation devices also work to resolve many issues associated with self-generated noise. Always remember, HVAC noise is not necessary. Solutions exist to solve the problem and the noise may just draw attention to larger issues that need to be solved.

Contact us at Metal Form Manufacturing today to learn more about how we can help you reduce your home or building’s self-generated noise.