10 Ways To Soundproof Your Air Vents And Ductwork Fast!

A noisy air vent can be the thing standing between you and good night’s sleep. In fact, more often than not, vent noises can reach up to 70 decibels right at the outlet.

That’s as loud as two people sitting next to each other and talking.

Which brings us to the question of soundproofing our air vents at home. Luckily, there are a couple things that can be done to considerable decrease noise.

10 Ways To Soundproof Air Vents And Ductwork

#1 Remove the vent

This only goes for non HVAC vents- you can choose to remove them altogether by plugging the space with drywall and/or some insulation.

Doing that will definitely stop the sound transmission. Keep in mind though, that you might face ventilation issues unless you crack open a window.

Also- this isn’t an ideal solution for a HVAC vent, as it will be part of a bigger network of vents, all of which are interconnected.

My suggestion: Consult a professional before going down this route with your HVAC vents.

#2 Get your ducts insulated

As sound travels, so does noise- with it.

Unless, that is, you line the surfaces of the ductwork with absorptive material that make it tough for sound to travel.

The other benefit of insulating  your ducts, is that you will probably end up saving money on electric bills. Sometimes, ducts tend to leak the temperature they are conducting into the surroundings, and so, a duct liner is needed to ensure that doesn’t happen.  

In fact, there are so many positive reviews on Amazon due to how well this product-Reflectix, insulates ducts. It’s the most popular duct liner on Amazon and it’s also pretty cheap.

Another important benefit of getting a duct liner is that it makes your HVAC system more efficient, and you’ll ultimately save on electricity. Win win.

So, how useful will you find a duct liner?

While you will see a noticeable difference, such as demonstrated in the video below- if the noise is quite loud already, it won’t be a significant ENOUGH reduction.  

Now, keep in mind that when I say loud, I mean in the 70 decibel range, which is roughly how loud a human conversation seems- when there are two people sitting nearby.

However, if the sounds you want to block aren’t as loud- say they’re a moderate irritant rather than a loud 70 dB(ish) noise, this really should do the trick for you.

#3 Cover your vent up

Get a magnetic vent cover. While you shouldn’t be covering up multiple vents around the house as it will build up air pressure in the HVAC  ducts- doing so for one or two won’t make a major difference to airflow.

I liked this magnetic vent cover on Amazon. It comes in a pack of 5 and is 8”x7”. It definitely also had the most satisfied customers, overall.

It’s only suited for steel grilles, so if you have an aluminium, plastic, wood grille or even a steel grille that’s painted over, you’ll want to get a new steel grille from amazon as well.

#4 Get a duct silencer

Duct silencers such as this one by Phresh, can be attached inline next to the fan.

Fancy terminology aside- it’s basically an air filter that has sound absorption properties.

Phresh claims it can reduce up to 50% sound in your ducting.

Also, a lot of people seem to buy simply because it also spreads a nice odor in the house. Check it out on Amazon

#5 Flexible ducts

Sound always travels in a straight line. So, if you introduce a couple of bends and curves in its path, the sound transmission gets greatly decreased.

That’s why you definitely should consider getting flexible duct in at some places around the house, which are the hotspots for noise activity.

In fact, this will probably be even more helpful than lining the ducts.

One drawback to flexible ducts is that they are prone to breaks/leakages at the bends-  so you’ll have to be careful about that and patch up any leaks that may occur.

To this end, you may want to check out this product on Amazon,

#6 Upgrade HVAC system

If you have an old HVAC system, that could also be part of the reason why you have noise coming in.

The newer systems are much more quiet, and while yes, it will be a big investment-  you can look at recouping some of the costs of the older one by finding second hand HVAC dealers

#7 Bonus duct soundproof technique(Video Only)

#8 Sound Maze

Creating a sound maze is quite a popular option, but one that requires you to be a bit DIY.

It basically consists of a rectangular box in the dimensions of your ductwork, that contain  multiple wooden slats placed at an angle, one after the other.

These wooden slats are covered with sound absorptive material such as acoustic foam. This is done because placing a tortuous path for sound to travel through decreases it’s transmission significantly.

It does work, but if you’re like me- you’ll need to get a professional for this.

Sound Leakages Through Ductwork

#9 Soffits

These are basically enclosures that go around your ductwork. Essentially, you are creating a barrier between the ductwork and the room. You could even line it with soundproofing material, such as MLV.

#10 Seal the gaps in ductwork

Like I said earlier, if you notice a hissing sound, it probably is due to leaks in your ductwork.

You can easily remedy this using a sealant foam and some duct insulating tape.

This video explains it all:

The 2 Types of Air Vents You’ll See At Home

#1 Ventilation vents

An above door air vent, for instance, is meant only for cross ventilation between rooms, and generally is quite short as compared to HVAC air vents. Soundproofing these type of vents isn’t a big deal- you can simply block them with a magnetic vent cover, say.

#2 HVAC air vents

HVAC air vents consist of transfer vents and return air vents. Basically, one outlet vent in a room is designated for transferring the cold air into the room that is being generated by the air conditioning unit.

The second air vent, called the return air vent is used to suck in the warm air in the room and circulate it through the air conditioning system to cool it down. This cold air is then sent back out through the supply vent.

Similarly, when the conditioning system is set to heat the house, the return vent sucks in the cold air in the room and brings it to a consistent temperature with the rest of the house. You get the idea.

Why sub-optimal air flow in HVAC ducts causes noise

If there are places where air can leak out of your HVAC ducts, there will be noise.

Also, inefficient air flow inside the ducts is a major cause of noise as well as it results in build up of air pressure in some places in the ductwork.

This is why it is crucial that there is optimal air flow in your HVAC ducts.

This factor isn’t as crucial for your non HVAC vents, as they’re just for cross ventilation and don’t have pressurized air flowing through then.

8 Common noises in your HVAC system and what they mean

#1 HVAC makes a loud slamming noise

If you hear a loud slamming noise as soon as you turn on/ turn off air conditioning, it probably is the sound of your air filter slamming against the grille.

This could happen because of a couple of reasons:

    • Your air filter is too restrictive and hence is blocking airflow. This would lead to a buildup of air pressure right at the start and end of operation of the air conditioner  which can suck the air filter into the side of the vent.
    • Your air filter could also be restrictive if it hasn’t been cleaned for sometime, as dirt particles stuck in it could be blocking airflow
    • Your ducts are undersized for the volume of air that is being pushed through them. If this is the case, you are going to need to get professional help

If this slamming sound persists throughout and isn’t just limited to when you start and switch off the system-  then it could be coming from the HVAC’s blower assembly. In this case you should switch off the system completely and get a professional to look at it.

#2 HVAC makes hissing sound

A hissing sound most probably means that there is a leakage in your HVAC ducts.

Like I said earlier, having optimal air flow and no leakages in your HVAC ducts is important- otherwise the cooling/heating won’t be efficiently done.

You’ll probably end up with a higher electricity bill because the system has to work harder to provide the same level of heating /cooling

Really, assessing your ductwork is a precise task and should be done by a professional.

#3 HVAC makes popping sounds

If you hear popping sound when you switch on the HVAC system, in most cases it is going to be because of the metal in the ductwork is expanding.

This isn’t detrimental to the system and if you can ignore it, you should.

However if the noise is too much, you can line the ducts with insulation, get flexible ducts instead.

Actually- you know what?

Let’s not get ahead of ourselves as there are COUPLE of things that you can do here. I’ll get into them later in this post.

#4 HVAC makes rattling sounds

A rattling sound in your HVAC system can mean that there are some loose particles inside the ducts-like a loose screw.

If, instead of a rattling sound you hear a low screeching, it could be the sound of something bigger than a screw being dragged around inside the duct.

If you have a bit of DIY experience, you could possibly open the duct if you can pinpoint where the sound is coming from, and try to remove whatever is making noise.

If not, you’ll need to get a professional for this.

#5 HVAC makes rapid clicking sounds

Rapid clicking sounds when you just turned on your HVAC system are normal but if they continue to persist- they’ll usually be coming from your compressor or control panel, which can mean that your system relay is not getting the right signal.

Again, not an issue you can solve by yourself .

#6 HVAC makes a squealing/screeching sound

This could be because of a bad belt or motor.   try lubricating these parts with wd40, and if the sound still persists- get a technician to look at it.

If you need to replace a part or two it probably won’t even be an expensive fix

#7 HVAC makes a buzzing sound

If your HVAC system is making a buzzing sound, it could be that the source is your compressor/ blower system and the sound emanating from it could be traveling down your ducts.

One of the reasons this can happen because your compressor is getting old.

If that is true, there is very little you can do really outside of actually replacing the compressor-  which can be an expensive fix.You can only know for sure if you get a professional opinion.

A good solution, if it is the compressor is to get a soundproof blanket for it- such as the Brinmar, which I wrote about in more detail in this article.

#8 HVAC makes a rumbling sound

Rumbling sounds could possibly be made because of soot or carbon particles getting stuck in the burner, as the HVAC system heats the house. This blocks airflow, which in turn makes the rumbling sound.

If you haven’t done this in some time, you should turn off your HVAC system, and vacuum the dust off of the burner, blower compartment and furnace base.

Conclusion

There can be many many more ideas as to how you can soundproof your ductwork and air vents- however, I tried in this article, to present you with to most people.

If you have to pick just one thing from this list, I would say go with flexible ducts. Given my research, I believe it’s the most impactful thing that you can do.

Now- that’s all I have to write on this topic but:

What about you guys? Have you faced a similar problem earlier? I would absolutely love to hear about it(and maybe even add it to the article, if it’s something I’ve missed!)

However, it’s important to look at the types of vents present in our homes and what are the common causes of the noises they might make.

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