Vibration From The Condenser Unit

[natera]

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!

[Bazooka Joe]

Was the pad always flush with the ground, or you never noticed? Typically pads are elevated higher than the ground. ( 2”+ inches ) Those pads have styrofoam on the undersides. A solid concrete pads weight a ton and those ultra lights are popular nowadays.

UltraLite® pads are durable, fiber reinforced cement pads that flex instead of cracking or breaking. They include a textured surface to prevent equipment sliding and are unaffected by environmental conditions.

How old is the system?

Possibly the pad was elevated higher when they initially installed it and quiet, and as time marched on the vibration and weight sunk the pad and stressed out the lineset to where it makes noise now. Even running and securing linesets is an art. The install guides of the outdoor unit usually gives specific guidelines on how to secure linesets and even when it penetrates a outside wall.

Looks like your unit had some prior work on it as one sheetmetal screw on top side is a different color than the rest.

When was the last time you had a basic PM check on your system. Maybe they ( Contractor ) can elevate the outdoor unit and install some vibration pads to see if that helps?

Someone here mentioned that pads sink in over time due to weight of machine and vibration.

[BNME8EZ]

have you traced the line inside the house to where they connect to the coil. I have seen lines carry a vibration and somewhere along the route they touch a framing member and that serves as a sounding board then amplifying the sound.

[Mr Bill]

I've stopped those noises by just sliding the condenser over a bit, from one side or the other about an inch or so, I've seen it work many times.

[natera]

Was the pad always flush with the ground, or you never noticed? Typically pads are elevated higher than the ground. ( 2”+ inches ) Those pads have styrofoam on the undersides. A solid concrete pads weight a ton and those ultra lights are popular nowadays.

UltraLite® pads are durable, fiber reinforced cement pads that flex instead of cracking or breaking. They include a textured surface to prevent equipment sliding and are unaffected by environmental conditions.

How old is the system?

Possibly the pad was elevated higher when they initially installed it and quiet, and as time marched on the vibration and weight sunk the pad and stressed out the lineset to where it makes noise now. Even running and securing linesets is an art. The install guides of the outdoor unit usually gives specific guidelines on how to secure linesets and even when it penetrates a outside wall.

Looks like your unit had some prior work on it as one sheetmetal screw on top side is a different color than the rest.

When was the last time you had a basic PM check on your system. Maybe they ( Contractor ) can elevate the outdoor unit and install some vibration pads to see if that helps?

Someone here mentioned that pads sink in over time due to weight of machine and vibration.

I think the pad has been higher above the ground in the past, might be also the reason why I didn't notice the vibrations before. Last winter we had a lot of snow so maybe the extra weight and soil moisture when it was melting caused it to sink.

What would be the right way to isolate the linesets where they penetrate the wall?

[natera]

I've stopped those noises by just sliding the condenser over a bit, from one side or the other about an inch or so, I've seen it work many times.

By noises do you mean condenser noises that can be heard from the unit like metal rattle or noises that can only be heard inside but outside by the unit appear as vibrations only?

[natera]

have you traced the line inside the house to where they connect to the coil. I have seen lines carry a vibration and somewhere along the route they touch a framing member and that serves as a sounding board then amplifying the sound.

I did trace them and it seems like they don't touch much, maybe just a couple of spots where the foam insulation over the pipe is touching but it doesn't seem to transfer vibrations there beyond a couple of inches.
At the wall penetration, is there a special method to isolate the lines from the siding/frame?

[natera]

Just found that the company that sells the UltraLite pads (DiversiTech) is also selling an Anti-Vibration small pads: https://www.diversitech.com/en-US/category/cat_id/209

Probably would be the best course of action to try next.

Any recommendations for safe methods to lift condenser corners a couple of inches to slide these pads?

[Mr Bill]

noises that can only be heard inside but outside by the unit appear as vibrations only?

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This.

[Bazooka Joe]

I think the pad has been higher above the ground in the past, might be also the reason why I didn't notice the vibrations before. Last winter we had a lot of snow so maybe the extra weight and soil moisture when it was melting caused it to sink.

What would be the right way to isolate the linesets where they penetrate the wall?

The install guide usually gives specific instructions on how to do that, ( penetration through wall ) thinking it’s kind of late for that now, especially if you never heard the noise till recently. May try the vibration pads 1st and even what Mr. Bill mentioned, moving the outdoor unit slightly. Don’t know why you would need to elevate unit 2” as pads are typically no more than 1” tall?