How to Quiet a Noisy Air Conditioner
Every spring and summer, as soon as the weather warms up, we take more and more calls from people looking for solutions to a very common issue: how to quiet a noisy air conditioner. Especially in the early spring, the noise level from parts like the condenser or compressor is troublesome because some people are running their air conditioner unit while others are opening their windows. The constant drone of the machine can even be bothersome enough to drive neighbors to their breaking point. Luckily, there are different methods of control and reduction of excessive sound you can take to mitigate AC noise.
When it comes to reducing AC noise, eliminating or significantly reducing the amount of sound is definitely possible and really not all that difficult to accomplish. However, your approach to this type of noise reduction must be done correctly. Depending on your home, please keep in mind that all installations are going to will require some site-specific customization, but the guidance below should hopefully point you in the right direction.
Finding a Solution For Your Noisy Air Conditioner
Let’s begin with an example. In the Midwest, air conditioning units are typically installed outside on ground level, somewhere near the house––and most often, on the side of a house near a neighbor. When the air conditioning unit turns on, parts like the AC compressor outside come alive, generating a fair amount of mechanical noise. Whether the house’s exterior has siding, concrete, wood, or stucco, the sound tends to bounce off the house and usually heads directly toward neighboring windows. So, not only are you dealing with the noise of your own air conditioning unit, but you may start hearing air conditioner noise from your neighbors, too.
To address this type of excessive noise, you will need to build an “enclosure” around the unit. This will require a bit of construction on your part, and there are a few things you’ll want to consider before beginning the project:
- Acoustical performance to prevent inhibiting the operation of your system and aesthetics.
- The distance of the enclosure from the unit and condenser.
- The number of walls and their height.
- The type of wall, fence, or enclosure to build (and whether you or a hired professional will build it)
- The types of products to use to line the enclosure
Building an Enclosure
The first thing to consider is the location of the walls of your enclosure – which is the most critical aspect of approaching this situation. The purpose of your HVAC’s parts, like the compressor outside your house, is to cool and compress the Freon in the AC lines. This is why the large volume of air coming from the top of the unit is warm. If that airflow is inhibited, you can seriously damage your HVAC system. These parts of your unit need a certain distance around (and over) them to allow the system to operate correctly and to service the unit – so if you have any questions, don’t hesitate to contact a local HVAC contractor for expert advice.
Number of Walls
Once you have decided on the distance of your privacy fence from your unit and the type of fencing that you will use, it is time to decide the number of walls you are going to build. If you are going to go through the trouble of constructing walls, build three walls in the shape of a “C” if you were looking down at the unit. That was easy, wasn’t it? It would be a good idea to put the two side walls (the walls extending out from the house) on heavy-duty hinges so they could be swung open in case someone needed to service the unit.
One of the more difficult questions to answer is the height of the walls that you will build. This is a little bit more difficult to answer because you have the exterior aesthetic of your yard to maintain. The height of the noise source will dictate the overall height of the walls. That being said, from an acoustical standpoint, you’ll need to eliminate the “line-of-sight” sound travel.
No matter what kind of acoustically absorbent or “soundproofing” product you line an enclosure with, if you can still see the unit, you are still going to be able to hear it. Therefore,if you are considering building walls only (i.e. no roof), we recommend constructing a wall height double the noise source’s height. For instance, if your AC unit is two feet tall, your wall height should be four feet. If that is not possible, which often it isn’t, the higher, the better. If you need a shorter overall enclosure, we suggest making an angled roof over at least part of the unit or parts like the compressor. If you can imagine the top of a backstop for a baseball field, that is the type of overhang we are referring to.
The Acoustical Treatment: Picking the Right Products
Now that you’re familiar with the construction requirements for your wall enclosure, it’s time to learn about the different products that can be used outdoors to treat the inside of the enclosure itself. At Acoustical Surfaces, the two most common and effective products we recommend are our Sound Silencer acoustical panels and the Exterior Grade Sound Blanket––both of which require a type of substrate to attach to. We’ll break down each of these products below:
Sound Silencer Panels
The most common lining for the air conditioning enclosure is the Sound Silencer acoustic panels. These are rigid boards made from a hollow, expanded polypropylene bead and will require a sheet of plywood to attach to. The plywood will act as a good noise barrier coupled with the sound silencer, but more as a structural element to support the panels than anything else. The panels can be installed onto the plywood with a construction-grade adhesive like our PSA-29, or be screwed through and into the plywood. If you are installing these panels, we would strongly recommend making the walls of your enclosure out of 3/4″ exterior grade plywood and sealing up all the air gaps with a sealant.
The Sound Silencer panels come in a 1″ and 2″ thicknesses and are sold in 2′ x 4′ panels. The 1″ thickness normally sells for about $5.50 per square foot, or $44.00 per panel, and the 2″ thickness sells for about $9.60 per square foot, or $60.00 per panel. They can be cut with a table saw or skill saw. Cutting the 2″ panel can get tricky, so please call to discuss the installation details. The 2″ Sound Silencer panel is rated with an STC of 13, and an NRC of .70.
One important thing to keep in mind about the Sound Silencer panels is that if they are exposed to a large amount of sunlight, the polypropylene will start to break down over time. This can happen faster with the white panels. In this case, we recommend using this type of panel to line the inside of a solid structure such as plywood or a privacy fence to keep the panels out of direct sunlight. Otherwise, we recommend only using the charcoal color for exterior applications. The charcoal dye acts like a window tint, protecting the polypropylene from the sun. If the area is shaded for most of the day, or if the panel has a roof, you will be fine with this product. It will be the most effective when backed with a solid board of plywood rather than spanning gaps in a privacy-style fence.
Exterior Grade Sound Blanket
When it comes to quieting a noisy air conditioner, our best product is the BBC-EXT-TR2 Exterior Grade Sound Blanket. These sound blankets have panels that are constructed by stitching a 2″ (nominal thickness) fiberglass layer to a 1/8″ thick, 1# p.s.f. Mass Loaded Vinyl noise barrier. The fiberglass is encapsulated in exterior grade vinyl – similar to that used for covers for a boat or cooking grill. We install grommets through the top, middle, and bottom of the panels and sew an exterior grade vertical Velcro seam along the left and right of each to attach one panel to the one next to it. These panels are intended to be installed outside and last for years and years without breaking down or failing. If you have an eye for aesthetic design, we can use a few different colors of vinyl for the backing: (standard) Gray, Tan, Green, or light blue. We can also use a few different colors for the quilting: (standard) Gray, tan, or black.
Additionally, the BBC-EXT panels are all custom-built to whatever measurements and sizes you––so they will line your enclosure perfectly. The vinyl backing is intended to be mounted to a chain link or alternating board-style privacy fence. The fiberglass quilting should face the noise source and is very effective at absorbing the reflective noise within the enclosure. Both the vinyl and the fiberglass are important to the product’s performance. The vinyl blocks the sound, and the fiberglass absorbs the sound. If one were to build a concrete enclosure, the sound would bounce around in the enclosure and spill out over the top. Want to learn more about how fiberglass compares to other products? Check out our blog to discover the differences between mineral wool vs fiberglass for insulation.
Absorbing the loud air conditioner sound with the enclosure greatly reduces sound leakage over the walls. Regarding the cost of this option, it will ultimately depend on the quantity and size of the panels needed. The ballpark cost for these panels is about $18.00-$20.00 per square foot. The overall cost will directly relate to the size of panels you need. While this option is more expensive, it is effective and echoes the ‘you get what you pay for’ mindset.
Quiet Your Air Conditioner With Acoustical Surfaces
When deciding which of the products above is best for you, the Exterior Grade Sound Blanket solution will outperform the Sound Silencer panels in most instances simply from an acoustical standpoint. However, the applications are not normally an apples-to-apples comparison. We also offer curtains and acoustic blanket panels with an STC of 27 and an NRC (with the 2″ facing) of .85.
If you’re looking for more information, reach out to our team of experts for guidance on silencing your air conditioner so you can enjoy the cool air from your air conditioner (noise free) as we approach the hustle and bustle of spring and summer.