Author Topic: Buzzing in Condo Walls from HVAC  (Read 14504 times)


  • Guest
Buzzing in Condo Walls from HVAC
« on: November 24, 2006, 12:40:00 AM »
Hello, I'm wondering if anybody can help me with this problem.  It's driving my wife nuts.  We recently purchased a condominium, and when the upstairs neighbors run their HVAC system (each condo unit has it's own HVAC system in a closet in the unit) we hear a low buzzing sound that sort of pulses in our apartment.  It's close to being imperceptible, but it is just audible enough to be annoying.  When I put my ear against the walls in our condo I can hear a strong buzzing/vibrating sound, so it seems as if the noise is coming through the walls from the unit above us.  I am trying to figure out how to eliminate this annoying sound.  I am considering putting a layer of drywall plus GreenGlue over the existing walls, at least in the bedroom, so that we can get a decent night's sleep.  Another thought from an HVAC technician I spoke to is that perhaps the buzzing is coming from the upstairs neighbor's HVAC compressor, and he suggested talking with the neighbor about putting a 'compressor blanket' around their compressor.  
Any thoughts, ideas, opinions?  I would really appreciate any comments.


  • Guest
Re: Buzzing in Condo Walls from HVAC
« Reply #1 on: November 24, 2006, 05:03:49 PM »

The Green Glue and Dry Wall is certainly one option available to you. The other option is that of lining the neighbors air conditioning unit walls with a Closed Cell Fom 1" thcik that will help absorb some of the motors vibrations.

It is  your choice as to which remedy you go with. The Green Glue/Dry Wall approach requires no one elses approval. In  the case of encapsulating the air conditioner unit, you will need the neighbors consent.

Take a look at the following and then call with any questions that you have concerning these matters.

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  • Guest
Re: Buzzing in Condo Walls from HVAC
« Reply #2 on: November 24, 2006, 09:30:07 PM »
Sounds like a nest of killer bees to me.  You should sell now...

The pulsing, buzzing noise is definitely coming from the compressor.  In operation, neither the coolant or air flowing through ducts will make that type of noise.  Either the compressor is simply vibrating the structure or the vibration is somehow travelling down an uninsulated copper freon pipe rubbing up against a stud/plate/joist.  

I say do the cheapest option first.  Ask your neighbor about taking a look at his compressor and seeing if you can mount it in a more resilient way.  If the compressor is attached with brackets and screws, a 'compressor blanket' won't dampen the vibration, which is all structure-borne.  You have to change the way it's mounted.  

Or, if you have the money, do both - resilient mounting & a blanket.  I think that should pretty much solve the problem.  If not, the problem is buried in the walls somewhere.  Then go the Green Glue route.  

Also, your a/c is probably irking someone else in the same way.  To be neighborly, you should take care of yours too.


  • Guest
Re: Buzzing in Condo Walls from HVAC
« Reply #3 on: December 01, 2006, 12:26:01 AM »
Hi thothboy,

The replies so far are right on.  For vibration isolation pads and discussion see  If the HVAC unit is properly isolated from the floor/walls with anti-vibration mounts then the compressor "pad" would be the next step.  And lining the walls/ceiling with SSP Mat.

The great aspect of adding Green Glue and dry wall to your existing bedroom walls is that Green Glue lowers the resonat frequency of the wall assembly.  In other words it does a great job blocking bass frequency sound - in the 30-80 hz range.  Since what you are hearing is a "low buzz" the Green Glue would stop it from coming through the walls.