How to Quiet Noisy A/C Compressor

Please keep in mind this is my quick Photoshop sketch simply to illustrate the theory explained below.

As the weather heats up, and summer gets into full swing, we are getting more and more calls as well as E-mails about air conditioning compressors bothering home owners as well as neighbors. The problem can be fixed fairly easily and inexpensively, but either way, it needs to be done correctly. In some cases, doing ALL of the things that I will discuss below are not possible, so you have to do the best you can with the limitations of your situation. If you have questions, please feel free to contact me  to discuss the particulars of your problem. Often times digital pictures of your area are a great help.

Here in the Midwest, air conditioning units are installed outside on ground level, somewhere near the house – and most often, on the side of a house that is near a neighbor. When the air conditioning turns on, the compressor outside comes alive, which generates a fair amount of mechanical noise. Whether the exterior of the house has siding, concrete, wood, or stucco, the sound tends to bounce off the house and usually heads directly toward neighboring windows.

To fix this problem, you are going to need to build an “enclosure” around the unit. This will require a bit of construction on your part, and there are a few things to consider – acoustical performance, not inhibiting the operation of your system and aesthetics.

The first thing to consider is the location of the walls of your enclosure – which is the most critical aspect of approaching this situation. Now, I’m not an HVAC Contractor, so please forgive me if I am not exactly correct here… The purpose of the compressor outside of your house is to cool and compress the Freon in the AC lines. This is why the large volume of air coming out of the top of the unit is warm. If that airflow is inhibited, you can seriously damage your HVAC system. The compressor needs a certain distance around (and over) it to allow the system to operate correctly and for servicing the unit – so if you have any questions, please contact a local HVAC contractor for advice.

Let’s talk about the walls of your enclosure…

The first two things to think about – from an acoustical standpoint are that you need to eliminate the “line-of-sight” sound travel. No matter what kind of acoustically absorbent or “sound proof” product you line an enclosure with, if you can still SEE the unit, you have not chosen the most efficient approach. I understand that sometimes this is not possible, but I wanted to point out that it is definitely ideal. If you are considering building walls only (i.e. no roof) I would suggest a wall height that is double the height of the noise source. For instance, if your AC unit is two-feet tall, your wall height should be four-feet. If that is not possible, which often times it isn’t, the higher the better. If you need a shorter overall enclosure, I would suggest making an angled roof over at least part of the compressor. If you can imagine the top of a back-stop for a baseball field, that is the type of overhang I am talking about.

The acoustical treatment…

We have two different products that can be used outdoors to treat the inside of the enclosure – both of which need some kind of substrate to attach to. The most common lining for the air conditioning enclosure is the Sound Silencer acoustical panels. These panels come in a 1″ and 2″ thickness, 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 $7.50 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 just a little tricky, so please call to discuss the installation details. This panel is going to need a sheet of plywood to attach to – and can attach with a construction grade adhesive (PSA-29) or simply with screws and washers. The 2″ Sound Silencer panel is rated with an STC of 13, and an NRC of .70.

There is one quality of the Sound Silencer acoustical panels that you need to consider when thinking about using this product. We have found recently that with prolonged ultra violate exposure; the polypropylene core of the panel starts to break down. This happened MUCH, MUCH faster with the white, so for exterior applications, ONLY use the charcoal color. The charcoal dye acts like 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 is going to be the most effective when backed with a solid board of plywood, rather than spanning gaps in a privacy-style fence.

Another, and more costly lining is our Exterior Grade Sound Blanket. This product is commonly used on chain-link or privacy style fences. This panel is constructed by quilting a nominally 1″ or 2″ thick layer of light density fiberglass to a 1/8″ thick, Gray, reinforced layer of mass loaded vinyl. We make these panels specifically to the sizes needed on a per-job basis. Our most common application for this product is around large air-handlers for commercial applications simply because these machines normally have chain-link fences around them. When we fabricate these panels, we will pound grommets through the top, middle and bottom of each, and line the vertical seams with an exterior grade Velcro to attach one panel to the one next to it. Because these panels are made on a per-job basis, I would rather provide a quote based on your measurements than on a ballpark price, but if you would like some idea, the cost usually falls in the $14.00 per square foot neighborhood.

The Exterior Grade Sound Blanket solution will out perform the Sound Silencer panels in most instances simply from an acoustical standpoint – but the applications are not normally an apples-to-apples comparison. The Quilted Curtain panels have an STC of 27 and an NRC (with the 2″ facing) of .85.


55 Comments

  1. cfcitywide

    I seriously enjoyed this article. This is not some spam BS. I own a heating and cooling company in Chicago and we have been getting a lot of inquiries about sound from ac condensing units and what to do about it. After being in the business for over 40 years it didn’t really occur to me to build a absorber wall for the unit. We have used compressor blankets that the mfg’s provide and the results are poor at best. I was out at the Goodman mfg plant in Houston Texas where I was able to take a tour which included their sound testing lab. It was impressive and used some very sensitive equipment to measure db’s and frequencies. It seems that after seeing that I realized a bit more about the way the vibrations travel and the blankets can only do so much. I will without a doubt offer this as a possible solution to this menacing problem. thanks for the tip. I would like to know if I may use this info on my website?
    Mitchell Moore
    Citywide Supply & Service
    Chicago AC Repair

  2. eric wolff

    What about interior “whooshing” sounds coming from the interior vents and dealing with people with hypersensitive hearing and consider the loud rush of air coming out of the vents an annoyance?

    any ideas on how to difuse the noise?

  3. Ted W

    Eric,

    Quieting air flow is a much different approach than a noisy machine. To eliminate the air flow noise, either a soft duct lining needs to be installed into the duct or a duct silencer needs to be installed in-line with the duct system (like a large car muffler). Both are VERY difficult to try to get into a retro-fit situation. Is this a residential situation you are considering?

  4. Kay

    What about units that are on the roof? This is a condo building and the folks under me have their unit on the roof and I get to hear it thumping on and off
    all night.

    They claim it’s been checked and working properly…maybe so but the noise
    is unpleasant.

    Would this type of sound proofing work for roof AC units?

    We live in CA.

    • Julie

      I have the same issue of living in a condo with 4 AC condensers situated on the roof right outside my rooftop deck. The units vibrate the structure they sit on (which is the top roof of a covered walkway between condos) that is attached to my condo. The noise is crazy. The situation is under review by the HOA lawyers but until I get some word back from them, I’ve decided to move ahead on my own to resolve this issue. This blog is a start. Any ideas, anyone? Please, I’m desperate! Thank you!!

      • Ted W

        Hi Julie,

        I’m sorry to hear about your problem. There are a few things that could likely be going on here. Your mention of the units vibrating the entire structure is the most troublesome and should probably be addressed first. If you still have an airborne sound problem after that, you can take that as a next step.

        I would strongly recommend a series of spring isolators that will raise the machines off of the roof and allow them to shake and vibrate independent of the structure. The springs in this instance would work a lot like a car’s suspension — eating up a significant amount of vibration energy. There are a LOT of different options and models of spring isolators, so I would need to get more information from you about the machines, corner weight, where you are located, etc. You may be able to get away with housed spring mounts, or you may need a seismic or wind-load-rated mount which would be more of a custom order.

        If the vibration issue is resolved and you need to take the situation further, you will likely need some kind of exterior-rated sound blanket to stop the sound from “pouring” over the edge of the roof and down toward you.

        If you want to send me a few photos of the situation as well as your address (so I can get a Google Earth view of the situation), I would be happy to try and help further.

        Thanks,
        Ted

  5. don mixon

    I have noticed that on new units, one next door & one at a friends house, that the compressors are now being wrapped with some type of weather proof insulation much like the ones you can place around a water heater tank.. On both these units the humm is completely gone and you only hear the fan. My question is can you put one of these on a unit that is 5 years old to help quiet it down some. Thanks Forrest Mixon

  6. Tyler

    Kay,

    Thanks for your question. Ted, our normal blog writer, is out so I am replying in his place.

    I don’t believe the Quilted Curtains would help your particular situation. You see to have a vibration problem instead of an airborne noise problem. I would recommend isolating the unit from the roof so that it is not in direct contact with it. This will make it so that the vibrations the unit is creating cannot travel into your living space.

    To help reduce the vibrations, we do offer many different options, depending on the details of your specific situation. Feel free to give me a call and I would be happy to talk with you about your options.

    Tyler
    tyler@acousticalsurfaces.com

  7. Tyler

    Forrest,

    Thanks for your question.

    Unfortunately, I cannot answer that question. That really is a question for the manufacturer of the AC Unit. The specifications of the AC Unit determine the treatment that you can put on or around them. Again, this is not my industry, but the manufacturer will be able to recommend what you can do.

    If you have any other questions, let me know.

    Tyler
    tyler@acousticalsurfaces.com

  8. icehead

    Tyler,
    What if the noise problem isn’t on the outside of the house, but on the inside? Our furnace/air conditioner combo makes a lot of noise when it blows; is there anything we can do to minimize it?

  9. Dawna King

    Hi.. I live in an apartment on the top (fourth) floor and the condensers are above my unit. There are four floors and four condensers above my bedroom supporting each apartment. I am on the fourth floor. The noise impedes my ability to sleep. So I have been trying to discuss ways to muffle the sound with the maintenance crew. Any suggestions would be greatly appreciated. Thanks…

  10. Ted W

    icehead,
    There are a few things that you may be able to do to quiet down the system. I would probably suggest first calling an HVAC contractor to check out the system to make sure it is functioning properly. If it is, there are really only two other approaches. The first is to have a custom made in-line duct silencer fabricated and installed. These are basically like a big car-muffler for the system. It forces air past a duct lined and baffled with an acoustical absorber. Each unit is custom made based on the height, width, length and CFM (measure of airflow) associated with the duct. The other option is to line the inside of the duct with something like the Quiet Liner (http://www.acousticalsurfaces.com/quiet_liner/quiet_liner.htm?d=26) which is a recycled cotton roll that glues to the walls of the duct.
    Please let me know what additional questions you have.
    Thank you!
    -Ted

  11. Ted W

    Dawna,

    Sorry to hear that you’re having problems with your living situation. Just about EVERY time a similar problem is expressed to me, the only way to start to reduce the sound that is bothering you is to put each compressor (or the lot) on some kind of spring isolator which can significantly limit the amount of vibration energy that is currently getting into the structure. Typically these machines are not overly loud but because of the nature of the machine, they can introduce a massive amount of vibration energy that will transmit itself down, through the roof, joists and physically move/shake your apartment.

    There are quite a few different models and types of spring isolators but in most cases, one of the Type C Spring mounts are used: http://www.acousticalsurfaces.com/mounts_springs/spring_isolators_c_cip_ciw.htm?d=24 so that the machines do not fall off of the isolators.
    Please let me know what additional questions you have!
    -Ted

  12. Sari

    Ted…can you offer some thoughts on hanging the acoustifence on the enclosure surrounding ac units. The 6 ft x 30 ft size is perfect for my dimensions. Thank you for your info!

  13. AlliedAps

    Great post ! Building an enclosure works, and it’s pretty cheap. A simple frame made of 2×4 boards covered with 2′x4′ acoustic ceiling tiles (made for hanging grid ceilings) is a good start – put the “pretty” side of each panel toward the compressor – and don’t forget the floor and top of the box. Two layers would be twice as good (be sure to stagger the joints to keep sound inside).

  14. Franco Rosso

    Ted, I enjoyed reading your article. I replaced my entire home AC system and added a zone about 12 years ago, and they are damn noisy. The biggest problem is the vibration of the metal grills that cover the top of the units and hold the fans. The touch the metal sides of the condenser units and REALLY add to the noise. If I place my hands on the grill and push down the vibration stops and all you hear is the fan, which isn’t too bad. So…..I want to place some type of vibration reducing washers on the screws that hold the grills, or a gasket where the grills touch the condenser, but not sure if there is good material that someone has used before that won’t wear out quickly. BUT, there might be an even better solution that I haven’t heard of. I had a tech out here but he just said to stuff some rubber under the grills and that doesn’t work. Any ideas?

  15. Neal Andrews

    Ted, we recently moved into an apartment with an electric, water based heating and cooling unit (i.e. heat pump). It’s located in a closet in our living area, and while it works very well, it is very noisy. The closet has a luver door, which I assume is necessary for ventilation. I’d love to line the inside of the door to block the noise, but several people have advised me against it. What can you recommend to deal with the noise problem? Do you know of anyone in the Philadelphia area I could ask to take a look at my situation? Thanks for your help.

    • Ted

      Neal,

      I would assume that the louvered door is necessary to keep the machine from overheating as most louvered doors are installed for this reason. From an acoustical standpoint, there is not a door separating you from the noise source. I would strongly consult a local HVAC service tech to advise you what you can and cannot do.

      You may get some reduction by installing an absorptive surface on the side and rear walls of the closet as often times what happens in situations like this is that ALL of the noise being generated by the machine reflects off of the walls and comes out of the door. This scenario is much like a band-shell where all of the sound pressure only has one direction to go. Many people use the 1” or 2” Echo Eliminator (http://www.acousticalsurfaces.com/echo_eliminator/wall_panel.htm?d=0) on the walls of the closet to reduce this. These panels are very cost effective and do a really good job at absorbing sound.

      Thank you,
      -Ted

  16. Neal Andrews

    Thanks Ted; that’s what I thought you would suggest. I’ll give it a try.

    Keep your fingers crossed for me!

    Neal

  17. Katie

    I live in a 2nd-floor back unit in a big apartment building in NYC. On the back of the adjacent building, about 15 yards away, there are two machines — one old and one newly-installed — that are keeping me up at night. The old one goes on and off all the time, including the winter, and when it starts up, it makes kind of a “boing” sound & runs maybe 10 minutes at a time. I can’t see this machine to be able to describe it. What type of machine do you think this is? I can live with it, but it’s annoying. The second, newly-installed machine I’m having trouble tolerating. It has been running from 3:30am to 7am every morning, is a large vented thing and connects to a tube that runs around their building where I can’t see it. What kind of machine do you think this is? Do you have suggestions I can convey to our superintendent who can then convey them to the neighboring building? The machines and my apt unit are basically on the bottom of a narrow cement and brick canyon. Both buildings are 15 stories.

    • Ted W

      Hi Katie,

      Thanks for the question. Unfortunately, you will probably not like my answer.

      We can build custom noise barriers around these type of machines. I am not aware of what that specific machine is from your description. The problem with this solution that they are custom made and very expensive.

      I would suggest going to your city or superintendent and see if they will conduct a noise study and hopefully have them pay for the solution if it is bad enough.

      Thanks,
      Ted

  18. colin

    Hi Ted/ Tyler

    This is just the kind of info I have been looking for. I live in England where this is generally not such a problem, so not much info from UK sites. However, I recently had installed a Hitachi system which will be an aircon system in summer (assuming we get any warm weather then) but is also a heat pump working to heat the house in winter. And it is very efficient, produces a lot of heat for little power input and is very quiet inside our rooms. BUT, the outdoor unit can be really noisy when it is producing max output and the outside temp is down to freezing. It sounds like a small airplane! We can hardly hear it, but our neighbors are finding it a nuisance at night. I am also concerned about what it will sound like in summer if we get a hot spell and people have windows open. The unit is on our wall and quite close to their boundary. My neighbor is happy to help me find a solution. The only problem seems to be, is it practicable to import acoustic panels or blanket from the USA? Or is there a UK agent for your product, or anything similar?

    • Ted W

      Thanks for the comment! It’s great to hear that people still find these articles helpful.

      I would start by consulting with a local service person – someone who would come out to repair the machine in the event it was not working. Talk to them about your plans to build a wooden fence around the machine. Ask them how much room around the machine it will need to operate and if you will need to make any of the walls of the fence removable so that it can be serviced. Once that is determined, you can either build, or have a local company build a wooden fence around the machine outside. Depending on the type of fence that is built, this may or may not stop enough sound to make your neighbor more comfortable.

      If the fence itself is not enough, we will want to proceed with that on a per-job basis. I will likely need you to send me a few digital pictures of the area as well as the measurements (width and height) of the walls of the fence. I have even used Google Earth in the past to get satellite pictures of the buildings so that I have an even better idea of the area, distance, details, etc. In the event that the fence does not help to the degree needed, we would either need to fabricate a set of exterior-rated blankets and send them to you, or potentially help you try to source something locally.

      Thanks,
      Ted

  19. jennifer

    I found this article very helpful. Fiance and I just moved into a BEAUTIFUL, brand new green building in Brooklyn and we have a huge terrace with a view overlooking Manhattan. Summer is coming so I was excited to host some get-togethers out there, only problem is the SUPER noisy ac/heat air compressor or something. I don’t want to build anything too expensive or permanent because it is a rental plus, it is a NYC iniative of Middle Income Housing so any changes to the property would need to presented before a board. My estimate in measurements is 3ft in Length x 2ft in width x 2.5ft in height. Any suggestions? Please email me so we can discuss estimates in the blanket you mentioned? [email removed for privacy]

    • Ted W

      Jennifer,

      Very glad to hear you found this helpful. Sorry to hear about the problem you are experiencing on the terrace. You provided some measurements, but you did not explain what it was you were measuring.

      If you can SEE the air compressor, you will be able to hear it. Because of this, your noise barrier will need to introduce a line-of-sight-barrier between you and the noise source. You could use exterior-grade plywood to build a cost-effective and free standing wall that might help. The products that we have to offer for outdoor use are usually in the $14-16/sq. ft. range, depending on the product, dimensions, and options.

      Thanks,
      Ted

  20. Michele Peterson

    This is a question more than a comment. I recently began to notice a loud intermittent noise in my back yard. It kind of crept up on me, as it was new in intensity. It turned on and off every ten minutes, lasted a minimum of one minute, and was LOUD. I told my landlord, who said he thought it had to do with irrigation for his new orchard. He said he’d reset it so it didn’t run at the same hours. The problem has not been resolved, so I’m looking for ideas to contain the sound. The cylindrical pump is small, only around 17″ X 6″, but each time the noise starts up it’s like someone has started a truck and revved the engine for a minute or more. Thanks for any ideas.

    • Ted W

      Michele,

      You are likely going to need to build some kind of enclosure around the pump — making the walls and ceiling as dense and heavy as possible. If you use concrete block and fill the block with sand as the enclosure is being built, that would be the most effective and cost-effective noise barrier.

      We have a few products that can be attached to a wooden or metal-framed structure — the Sound Silencer and the Exterior grade sound blanket — reinforced which I discuss a bit in the article.

      Without knowing much about the situation, I would assume that you will need a minimum of a three-sided enclosure with a roof section — leaving the open end of the enclosure toward the orchard — or at least away from your house.

      Hopefully this helps — please let me know if you have any more questions or you would like to discuss the situation further. Thanks,
      Ted

  21. Roobik

    Hi Ted, I live on the top floor of this rental apartment in Burbank, CA. The folks under me have their AC unit on the roof next to bedroom, and the vibrations from the compressor in AC transmits into the roof and into my bedroom and also I hear constantly the thumping on and off of the compressor all night! the noise is crazy and impedes my ability to sleep.
    The AC crew have inserted small 4 pieces of rubber pads ( may half an inch thick) under the end corners to lift it from the platform and in addition they have placed a sound plate under the compressor in order to reduce noise and vibration, but these efforts have not yet reduced the vibration nor the noise. AC man also told me that he has placed some capacitors on the wires to reduce the thumping, but that hasn’t help the noise from thumping at all.
    I was thinking to tell the property management office to insert 4 pieces of Ribbed Neoprene and Cork ( 6″x 6″x 1″) under the machine or 4 Spring Isolators to lift up the machine off the platform, in order to reduce noise and vibrations, but I don’t think these will have any effects on reducing the THUMPING on and off !
    I would appreciate in advance your recommendations that I can transmit those to the manager.
    I has been a night me for me all this summer and if it’s nothing can be done I’m planning to move out!
    Thank you, and I will wait for your response,
    Roobik

    • Ted W

      Unfortunately, working from behind a computer and not being there to experience the problem has its limits. I am not going to be able to solve or even offer suggestions or recommendations fro ALL the problems and this is one of them. I’m sorry, but you are likely going to need to have someone there to see and hear the problem.

      Best of luck,
      Ted

  22. Kym

    Ted, you have some wonderful insights that are a great help to us folks who are trying to deal with these annoying situations. My situation is as follows and I would really appreciate you thoughts on how to remedy it. My wife and I live on the second floor of a condo building (contains only units). The owners of the unit below us have installed an AC handler (fan) in their ceiling (our floor). The condensor for the AC handler is located outside at ground level and I don’t think is playing much of a role in our problem. Whenever the AC handler in our floor is on our floor vibrates very noticeably and this vibration carries through our furniture. The construction of the floor is typical timber framing but with a thin layer (1 1/2″) of concrete forming the subfloor. The floor joists run widthwise, as expected, of what is essentially a rectangular floorplan. The owners of the unit below have had their AC tech out and he said that the fan and unit look fine and simply placed a few rubber pads on the corners (I assume) which really sisn’t improve things much. So it is now up to us to offer some type of remedy. I have been looking at spring-based hanger mounts and they seem to offer the most promise. Would you agree this and/or would you recommend any other strategies? One thing that is strange is that while the vibration is certainly strongest within a 10′x10′ area in the floor, the vibration actually carries across the joist bays and can be felt 25′ or so away on the floor. I also want to mention that we will be replacing our current carpet with wood flooring (or engineered flooring) in the near future and wonder how effective a dampening underlayment would actually be in this situation? … Looking forward to your insights on the whole situation… Thanks

    • Ted W

      Thanks for the complete description of the situation and problem! You are exactly right with spring hangers being the first step. These will allow the machine to shake and vibrate as it needs to without the energy carrying to the structure above. Without question, this would be the first step I would take if this were my issue. I would then take a step back and listen. Unless something else is carrying the vibration energy to the joists, I would feel pretty comfortable saying that this should eliminate the problem. Depending on the frequency that it is producing coupled with the structure, it’s not all that surprising that you can feel/hear the vibration 25′ away in the 10 × 10 room — there are a lot of very complex physics involved.

      Regarding the carpet and flooring — the Acoustik underlayment is probably your best bet there. This is an underlayment made from recycled rubber particles and is generally used to reduce the sound/noise from your footfall and similar impact noise(s) from getting downstairs. It would only be minimally effective at reducing the A/C fan problem that you discussed, since that is structure-borne vibration energy.

      Please feel free to let me know if you have any more questions. Thanks,
      Ted

  23. Eleanor

    Hi Ted!
    I was wondering whether you could offer me some practical advise. My situation is as follows:
    We live on the ground floor of a 2 story detached house. Our bedroom window is facing our (noisy) neighbours’ front door,living area and patio of their detached house – so we can hear everything from our bedroom. We tried to solve the problem by installing double-glazed windows, that were supposed to eliminate 80% of external noise (we wish!).Since we didn’t get satisfactory results, a friend suggested fitting a thick sheet of window-sized foam between the closed window and the external window shutter, which we could remove and fit whenever necessary. This muffles voices,which is good enough for us, but we can still hear the awful high pitch sounds of their TV. Is there anything you could suggest, preferably on a DIY level, that could solve the problem? I would really appreciate your expert advice. Many thanks indeed.
    Eleanor

    • Ted W

      I apologize for the delay, it has been amazingly busy around here lately.

      I’m having a hard time understanding the situation holistically. Are you currently being bothered in your bedroom from the noises that are being made within your neighbor’s house? How far away is your window from their front door? And, you can hear the TV that is inside their house? The details here just aren’t jiving with the picture that I have in my mind’s eye, which may or may not be even close to what is going on. But, if they are listening to their TV in their house (with the windows closed) and you are in your bedroom (also with the windows closed), and you are still hearing a high-frequency that is being generated 20-30 feet away and traveling through TWO closed windows — it must be extremely quiet in your bedroom or you have amazingly sensitive hearing. Again, I’m making some assumptions here, so correct me if I’m wrong.

      When the new window was installed, it’s likely that they shimmed the window into the rough opening and maybe put some insulation in the gap between the rough opening and the window jamb. I would pull the trim away, compress the insulation by pusing it into the gap, and finishing that joint with a non-hardening acoustical sealant or non-hardening construction sealant. I would also make sure the window was as airtight as possible.

      Sound travels first through any common air gaps and cracks — so be sure that your window assembly is as airtight as possible. The next path of least resistance is the area of the wall with the least amount of mass and density. You could potentially make a window cover out of sheetrock or 3/4″ MDF board. You could use some adhesive-backed weather stripping to make the window cover as airtight as possible. You can shine a light as a way to test for leaks coming through anywhere.

      Hope this helps. Thanks,
      Ted

      • Eleanor

        Thank you very much indeed for your reply.
        Yes,it is quite difficult to understand this particular situation,I totally agree, but I think you’ve hit the nail right on the head by suggesting a window cover made of sheetrock or MDF board. I’ll certainly give it a try anyway!

        Thanks again Ted,I really appreciate your help.
        Eleanor

  24. Anthony

    Hi Ted, I have a noise problem from my neighbors rooftop heat pump and want to see what your opinions are. I own a town house that has a shared roof with my neighbor and his heat pump is on top of his unit and mine is above my unit. Although his heat pump is not above my unit, I can hear the low frequency noise when it is on and especially when it kicks in and the noise is the loudest right at my bed. Heat pump is already on isolation pad and I am pretty sure the noise is structural borne since i can hear the vibration if i put my ear in the wall. I have read your comment on isolation springs but AC technician suggests I try sound blanket on the compressor inside the heat pump because he thinks there is no vibration and the blanket would help reduce a lot of the noise. Also he says installing springs would be expensive, around 2 grand because of all the labor involved. Do you think sound blanket would help? Or are springs the ultimate solution? Thanks a lot.

    • Ted W

      Considering your mention about being able to hear/fell a vibration when you put your ear to the wall, I don’t think that a compressor wrap/blanket is going to offer much, if any, reduction to the sound problem that you are experiencing in your bedroom. There is no doubt that lifting the equipment can get expensive, but it is almost always — and usually the only — way to start to reduce the problem. Another thing to consider is that if the machine is vibrating and there are pipes connected to the machine — the pipes can also introduce a vibration into the structure. It’s usually not as severe as the machine itself, but it can be an issue in some cases. You could absolutely TRY the blanket/wrap first and see what that does, and although it is true that every situation is different, I would guess that the best way to reduce/fix this problem is a set of spring isolators.

      Thanks,
      Ted

  25. Joshua Berry

    Great article. Between that and your response to comments I am a believer :-). I have a compressor unit right outside my bedroom window, about a foot from the exterior wall. The fan noise as well as the noise that occurs when the unit kicks on or off is particularly loud even with my window closed. I am hesitant to build too much if a barrier between my window and the unit because I don’t want to kill my view. Any recommendations?

    • Ted W

      It’s always best to try to stop the sound as close to the source as possible, but in this case it would likely inhibit the view from your window. I’m a bit hesitant to try to make this recommendation because there is a decent chance that the sound is coming through the wall of the house as well, but you could potentially start with one of our Climate Seal acoustical window inserts.

      It’s very common that the weakest link in a wall is the windows and it’s usually a logical place to start with for acoustical treatments/improvements. But because most AC systems produce a relatively loud and quite low set of frequencies, it may or may not offer a substantial enough reduction for your situation. One cheap and easy “test” approach would be to cover the window with a piece of 5/8″ sheetrock and use a standard sticky-back weatherstripping to make the sheetrock air-tight to the window. Leave that in place for a day or two and if it gives you enough reduction, the Climate Seal will block a bit more and be perfectly see-through and easily removable.

      If you’d like a quote or need more information, please let me know. I would simply need your address, phone number, the measurements for the window, and a digital picture or two.

      Thanks,
      Ted

  26. Jacqueline Eick

    Please answer asap anyone! The ac outside is silent, don’t know whether ac is broke? It feels like fan is only running! I can’t afford to have it fixed, please help!

    • Ted W

      It sounds like you may need to contact a local HVAC person to check it out. Sorry, we are not an A/C repair company and can not help with this situation. Best of luck to you.

  27. Michael Spencer MLA ASLA

    Hi Ted: I’d sure like to get advice and a quote on a couple of noise issues.

    First is our office- the reverb is awful! Bare tile floors and bare sheetrock (painted) with high ceilings. What would you need, a few photos?

    Also have a very noisy A/C unit. Looks like I found the right place!

    Michael Spencer

    • Ted W

      If you could send me the dimensions along with a few digital images of the office area with the echo/reverb problem, I would be happy to start that discussion with you. We have quite a few choices for different acoustical panels to help with issues like that and each has its own respective advantages and disadvantages, as well as costs and aesthetics.

      The noisy A/C unit is a different game all together. Digital pictures also help with that, and if you could send me a bit of information about the nature of the problem and details about the situation, that will also help.

      Thanks,
      Ted

  28. Roobik Gorjian

    Hi Ted, I hope that you’re doing fine. About 3 months ago you advised me on how to reduce vibration and noise from a noisy AC unit located on the roof next to my bedroom. You suggested to me that I should instal 4 Housed Spring Isolators in order to reduce vibrations from the compressor in the AC unit. I told the property owner about the vibration and noise in which impedes my ability to sleep, and a month later the owner installed 4 Housed Spring Isolators under the AC unit and in addition he added a sound plate under the compressor as well, and amazingly the noise from the compressor was reduced by about 60% , and this happened all because of your advise and I thank you for that.
    One more difficulty remains to be resolved and that’s the noise from the Initial Start of the compressor, another words every Initial Start of the compressor has a loud thumping noise and the AC mechanic doesn’t know how to fix this. Ted, do you have any suggestion of how to reduce the noise generated from the Initial Start of the compressor ? Does Thermostat has any bearing or effect on the Initial Start of the compressor?
    I thank you in advance for your suggestion.
    Sincerely yours,
    Roobik Gorjian

    • Ted W

      GREAT to hear that the spring isolators helped to reduce the noise. And, thanks for taking the time to let me know that it helped in your situation!

      Do you know if the start up noise is an airborne sound coming through the structure, or an initial vibration? Could you send me a few photos of the situation? That might help me make recommendations.

      Thanks,
      Ted

      • Roobik Gorjian

        Hi Ted, and thank you for responding to me so quickly. You asked me whether the start up noise ” is an airborne sound coming through the structure, or an initial vibration is an airborne sound coming through the structure, or an initial vibration?”.
        The start up noise is an airborne sound ( like a loud click ) coming through the structure into my bedroom and this happens when the thermostat turns on the compressor. The AC unit belongs to my neighbor below me and it’s on the roof over my bedroom.
        Ted, I’m not allowed to go to the roof to take pictures of the AC, but the contractor showed me the installed Spring Isolators, as you recommended those a few months ago.
        I hope that I’ve given you enough information about the start up noise.
        Thank you,
        Roobik

        • Ted W

          If it’s an airborne sound, you might benefit from putting something like an acoustical Quilted Curtain between the compressor and the wall.

          If you can space the panel off the wall by a little bit (even an inch is fine) that is ideal.

          The product is an exterior-rated barrier that will block noise as well as absorb the sound that hits it. They are custom-made to size and UV-stable components are used. Kind of like a backstop for a baseball field, the size of the blanket depends on the size of the compressor and the distance between the compressor and the wall.

          Let me know if you have any questions. I would need some idea of the dimensions that you need to put a quote together for you.

          Thanks,
          Ted

  29. Roobik Gorjian

    Thank you Ted for the information on Sound Blankets. If the property owner decided to go ahead with this I’ll let you know.
    Thanks again,
    Roobik

  30. carol hannah

    Hi! the basic drawing is just what I had in mind for my neighbors ‘noise maker”. she said it would be okay, then changed her mind. “everyone” keeps telling her it will block the air flow and raise her electric bill. my front porch is unusable. it’s very close and runs all the time. any ideas? thank you carol

    • Ted W

      I would have her talk with an HVAC contractor or the manufacturer. People put fences and enclosures around the condensers all the time. As long as this is done properly, which I discuss in the blog article, the machine will be just fine. You will need to get an enclosure with a noise barrier around the thing to use your porch.

      Thanks,
      Ted

  31. Debbie Davis

    Ted,
    We have two outside units which are elevated about 2 feet off the ground on a wooden platform. (flood area) The noise from the units is very annoying and i was looking to build a soundproof enclosure. I like your picture in the blog; is that PVC piping you are using in order to make the enclosure removable? Since you suggest a panel ‘double the height of the unit’, i would guess that if my units are 2 ft tall, i would need panels of at least 6 feet from ground to top…correct?

    Thanks for your help,
    Debbie

    • Ted W

      The white lines in the picture above are just me digitally modifying a photograph to show the idea I was talking about. As long as the PVC pipe is thick enough, there is no reason why it wouldn’t make a good frame for an enclosure. The curtains that we sell are UV-stable so you would not necessarily need to remove them, but that is up to you.

      Yes, your high assumption was correct. If the noise source is 4′ in the air, I would suggest a minimum wall height of 6′ off of the ground. The idea here is similar to a baseball backstop. The higher the fence, the more foul balls (or noise) it will stop.

      Thanks,
      Ted

  32. Debbie Davis

    Ted,
    One more comment…..I just went to the website to check out the pricing for the acoustic panels and it appears they are only sold by the box. Is that correct?

    Thanks,
    Debbie

    • Ted W

      The Sound Silencer panels are sold online in full box quantities, but I would be happy to type up a quote for as many or as few panels as you would like. I would also be happy to put together a quote for the quilted blanket, which would likely offer you more performance than the Sound Silencer panels.

      Thanks,
      Ted

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