Vibration From The Condenser Unit

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Aug 13, 2020
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Hello people,

I have an outdoor condenser unit (pictures attached) that transfers vibrations into my house framing whenever it runs and it's causing a low-pitch hum noise in multiple locations through the house.
The noise is something like the sound of a sub-woofer on low volume.
The sound levels from the condenser when running, compressor and fan, are as quiet as condenser can be, no issues there.
Everyhting seems tightened up well, I also looked at the pipes that go from the condenser through the wall and they don't seem to touch the wall too much, at least not to the point that I feel any vibrations around the opening or anywhere along their route to the inside unit.
As the condenser is on a platform as recommended it really puzzled me what can be the source of the vibrations but when I walked around the unit as it was running I've noticed that the ground around the platform is vibrating pretty strong, up to 4-5 feet from the platform to each direction the ground was felt like buzzing.
At this point I'm pretty sure that this is the source of what later translates to the low-pitch hum inside the house.
As I'm just an homeowner with no idea regarding HVAC, I have a couple of questions for you guys:

1. Might be that because the platform is low in the ground (as can be seen in the attached pictures) it causes a greater transfer of vibrations?

2. When I knocked on the platform I've noticed that althought it looks like concrete it's not a solid slab but feels and sounds kind of hollow. I can I understand why a hollow slab would be used, might be much lighter than a soild peice of concrete of that size, but is it a common practice to use something like that? I'd guess a solid, heavy concrete slab would block vibrations better but would like to hear from the experts what is the common practice.

Thank you all in advance!


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Well-Known Member
Nov 19, 2007
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most likely a fiberglass base designed to look like concrete. they are hollow underneath and will sink a little over time, about an inch. shouldn't have any effect on sound or vibration unless the unit is hanging from the line set but, this doesn't appear to be the case.
I go nothin', sorry.