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The air ducts and air conditioning systems in your building normally produce noise. However, the noise you hear inside your home will depend on how close or how far you are from your building’s air conditioning or HVAC system.
To reduce noise from return air in the vents, you can try opening the vents, cleaning the air ducts, resolving any ductwork issues, getting the right vents and grills, or reducing static pressure. If there’s no problem, you can buy a return air sound baffle.
Read on as we talk about the cause of the noise in the air duct, and how you can do basic troubleshooting. You will also learn some return air sound baffle methods and how to provide your return air grill with sound attenuation.
What Is Return Air?
Return air is what you call the air that has completed its circulation through a building’s air ducts. It starts as supply air from the furnace or air conditioning unit and returns to the HVAC system through the return air ducts for additional conditioning and ultimately for recirculation.
Supply Air Ducts vs. Return Air Ducts
To better understand the concept of return air, you need to know the difference between supply air ducts and return air ducts. These two are separate halves that make up the entirety of your home’s or your building’s heating and cooling air distribution system.
The supply air duct is responsible for delivering heated air from your furnace, cooled air from your A/C into each part of your house or building through the supply air vents.
After the air has passed through a room, the return air duct draws it out via a separate air vent then transports it back to your HVAC or A/C’s central unit to be heated or cooled again. The air then gets recirculated and goes through the same process again.
So, to put it simply, supply and return vents differ in terms of the airflow direction. In supply vents, the air flows out of the duct. Meanwhile, in return vents, the air flows into the duct. The air distribution system of your house or building is a closed-loop, and it continuously recirculates the same amount of air throughout the rooms.
Aside from conveying the air back to the furnace or the A/C, the return duct also incorporates the air filtration system, which ensures that you have good indoor air quality. The filter, which is typically behind the return vent, prevents dirt, dust, and other contaminants in the air from entering the HVAC system and causing damage.
What Causes Noise From the Return Air?
To hear some noise from your air vents when your HVAC system or A/C runs is normal. However, if you notice that this sound has increased in volume or has become a bit more bothersome with rattling, flapping, or any other unusual noise, it could mean that there’s trouble somewhere in the system. It is most likely due to increased pressure that is brought about by a restriction in the airflow.
As such, you must address the cause of noisy supply or return vents before causing any serious damage to your HVAC system. An HVAC system works doubly hard if there is no adequate airflow, therefore consuming more energy and becoming more vulnerable to damage and breakdowns.
Airflow restrictions may be caused by several things, which includes:
- Dirty air filter
- Closed or obstructed registers
- Closed duct dampers
- Debris stuck in the ductwork
Unusual noises may also be caused by leaky return ducts, which pull outside air into the ductwork instead of leaking air. As a result, extra air volume is added to the system, which tips the balance of air in the house.
There’d be positive pressure from neutral pressure, and the conditioned air gets pushed out of the rooms through small structural gaps and cracks. If this is the case, you will need to seal your duct.
If the noise coming from your return vents is not its usual noise or is louder than its usual volume, you might want to troubleshoot first. Let’s go over on what you need to do.
How to Reduce Noise From Return Air
Here are some ways you can reduce noise from return air:
1. Open the Vents
Two or more closed vents may put undue pressure on your HVAC system and make the noise louder, so checking them and making sure they are open is the easiest thing to do and should be your first step.
2. Clean the Filters and Air Ducts
If all the vents are open and you are bothered by the noise, you may need to check the ducts and the filters. Air is sucked into the return vents, so dust and other particles may have been caught in the filter. These particles may cause clogging, and this will cause your equipment to work harder. The harder your system works, the noisier it gets.
So make sure to clean and change your filters regularly. For a quick and simple clean, you can remove your vacuum and suck dust and other debris from your filter. You can also remove the grill and clean it more thoroughly.
3. Resolve Ductwork-Related Issues
Inefficient or poorly installed ductwork forces a lot of air into such a limited space, resulting in a whooshing or whistling sound. So you might want to call in a professional to check your ductwork and do any necessary repairs or corrective measures.
4. Get the Right Vents and Grills
The second easiest thing you can check is whether your return vents and grills are in their correct shapes and sizes. Vents should have ample opening to allow air to enter smoothly and should not close as easily. If the vents and grills are not the right size and shape, call in a professional to replace them with the appropriately shaped and sized ones.
5. Have It Checked by a Professional
If you cannot figure out what makes your return air vents noisy, get an HVAC professional to do the job. Whether it is excessive static pressure, an outdated variable-speed blower, a problem in the central return, a lack of return vents, or any other issue, an experienced HVAC guy will be able to fix it.
Don’t do any more trial-and-error or easy-fix solutions as you may end up doing more harm than good.
6. Soundproof Your Return Air Vents
If you find your air ducts and air vents noisy and there’s nothing unusual about the sound or volume, you can simply put a return air grille with sound attenuation. In other words, create a return air sound baffle.
Check out my guide on soundproofing air vents.
It is impossible to soundproof your vents without impeding airflow. As such, you really cannot cover your vent with any soundproof material.
Most air vents are loud because they are not made of sound-absorbent material. For example, metal is not a great choice of material for sound dampening. So you may want to put on a sound-dampening layer inside. You can ask your HVAC expert to do it for you.
For wall vents, you can cover them with soundproof curtains. These materials are more densely woven and are thicker than regular curtains. Put up a curtain rod on the wall above the vent, hang the curtain, and make sure it is long enough to reach the floor.
A professional can also plug your air vent using acoustic foam or build a sound maze inside the vent.
Noisy air return is common and normal if your air heating or cooling system is running. Nevertheless, you always have to pay attention to when this noise is getting louder or when unusual sounds get mixed in because that means there’s something wrong with your air vents or ducts.
There are easy and basic troubleshooting steps for people without experience in the HVAC department. But if it turns out to be more complicated than just closed or dirty vents, it’s wise to call in a professional to check and do the needed repairs.
If you want to reduce your otherwise normal air return noise, there aren’t many things you can do to soundproof the vents without hindering airflow.
The easiest thing you can do to lessen the noise is to hang thick or soundproof curtains over wall vents. More complicated soundproofing solutions are possible, but only best done by professionals.