Noise and inefficiency in air systems

At Ventx we understand that there is an inextricable link between noise and inefficiency in air systems. This is true whether it is a large HVAC system or a small air line. You may notice very loud noises coming from any air vent in the system. You need the right solution to tackle the problem. Luckily, we can help. We offer solutions that can improve efficiency and mean there is less noise.

What is the link?

In an ideal world fans in an air system will turn 100% of the energy they consume into air movement. However, when there is an inefficiency some of the energy will become sound. This is wasteful. The issue can also be compounded if the drop in air movement means a larger fan is necessary to get the rate right. The move to a large fan can mean even more energy consumption and more waste as noise.


The biggest cause of issues is bends in ducts. The change in direction will result in turbulence and reduce the air stream. In most cases people will choose a larger fan but this will make the turbulence worse. It is better to redesign the system to reduce the number of bends and their severity.

Having ducts that are too small can also cause excessive noise. The issue is that when the diameter of a duct is smaller it increases velocity. That can translate to more noise, especially when there is anything to disrupt the flow.

The fan inlet

A problem with the size of the fan inlet can also cause inefficiency. If it is too small it can restrict how much air flows into the fan and mean it needs to work harder to send a flow downstream. Ideally the inlet should be 1.5 times the size of the fan itself.

In addition, the inlet should be straight so there is no interruption to the flow. If there is a bend before the fan it can cause turbulence, noise, and inefficiency. The aim should be to get an uninterrupted air flow that can maximise fan efficiency.


Commonly people will select larger fans in an attempt to make a system quieter. While it can help in some situations, it can actually mean more noise comes from other sources. Usually a motor will drive the rotation of fans. These motors need to work harder to make larger fans turn at the right rotational speed. This can mean they consume more energy and make noise.

Ask us for an air vent silencer

Ventx is a team that can offer lots of different options for tackling noise. One is bespoke silencers that you can install in various locations in the system. They can provide attenuation, sound absorption, or a combination of the two. In addition, we can look at things like system redesign.

So, speak to us if you have a noisy air vent and want to reduce the sound and improve efficiency. We are an expert in our field and support clients in various industries.