How To Soundproof An HVAC System
Aug 01, 2022Soundproofing your HVAC system is one of the most confusing parts of soundproofing and one many of my students always have questions on. In this article I will demystify how to soundproof your HVAC system and give you some concrete principles that will help you with your design.
1) Increase Duct Size
The number one way to ensure you don't hear the air coming into your soundproof room is to make sure that your ducts are big enough, so that the air moves slowly through them. The goal is to have the speed of the air between 300-100 FPM or Feet Per Minute.
Let's look at an example. If you ventilation system is pushing out 100CFM or Cubic Feet Per Minute then you would want a 1 foot by 1 foot duct to get the speed of the air to 100FPM.
2) Right Angle Bends Introduce Noise
When your duct work makes a right angle bend it introduces turbulence which leads to air noise in your duct system. To reduce this try keeping your right angles at least 5-10 meters or 16-32 feet from your exit registers. If this isn't possible then just keep them as far away as possible. You can also use silencers to reduce the noise in a vent.
3) Use Round Ducts
Rectangular ducts create more turbulence and noise in the duct system. It is best to stick to round non-rigid ducting.
4) Baffle Boxes
A baffle box is a rectangular box that has several 90 degree angles that slow the air down and help reduce sound that travels from one room to the next through a duct system. They are great when your HVAC may be close to your soundproof room and you need a short duct system that is soundproof to get into your room. I used a baffle box system in my studio and it works great. Watch the video above to learn more about how to build a baffle box and get a feel for the design.
Conclusion
1) Create a large duct size to slow the air down
2) Don't make 90 degree turns in ducting close to your exit registers
3) Use round non-rigid ducting
4) Use a baffle box if your design would benefit from one
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