Neighbors air-to-water heatpump causing disturbing noise, any advice?

[Nick4191]

When it's cold outside, under around 2 Celsius (35,6 Fahrenheit), our neighbors air-to-water heatpump that is located 5 meters (16,4 feet) from our 2 bedroom walls, creates a disturbing rumbling noise that affects peace and sleep inside our bedrooms, even with the windows closed. The unit in question is a Mitsubishi ZUBADAN R32 (air-to-water heatpump), Model specification: PUD-SHWM100YAAR1. The issue is apparent during cold weather, and during the summer heat when windows are open. At these times the unit is working extra hard on high RPM and high effect, which causes it to generate a lot more noise.

dB measurements with a calibrated sound meter, when the issue is apparent:

1 meter (≈3.28 ft) in front of the heatpump-unit reads 69.8 dBA and 81,7 dBC

right outside bedroom window is 52.9 dBA and 67dBC

Inside bedroom 50.7 dBC

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Here is a recording of the rumbling noise from inside one of the bedrooms with the windows closed. Many speakers aren't able to play much of the low frequencies, if you play it on your phone speakers or cheaper end headphones, it's not going to be a good representation of the real noise:

https://jumpshare.com/share/YltTtCX40YX9pgHgaVWD
Also included as attachment (Air-to-water heatpump noise inside bedroom - without EXIF.wav)


Here is a frequency and loudness graph of the recorded noise. It shows how loud different frequencies are:

https://imgur.com/a/bPl0S8c

Also included as attachment (Noise profile - without EXIF.PNG)

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Anyone else have experience with a similar issue? Anyone have any advice on how to go about blocking this noise, would a concrete barrier in between the source and our house be a good idea?

 

[Trdat]

I'm presuming your in the States, in my country after 11pm anything over 65 DBA (measured from inside the house with windows open) is illegal and I am sure its similar in many places around the world. Check your local council regulations.

In terms of what else you can do, I would put double glazed Euro windows with the largest air gap between the two panes with one pane at least 10mm thick. Although that won't be very effective against the low rumbling noise it can mitigate it a little which might be enough, don't take my word for it though.

I'm not an expert on DBA, DBC, DB but from my understanding DBA omits/levels out the low frequencies and because the frequency reading is all low frequency content the DBA measurement is lower than the DBC and DB and most of these regulations are in DBA.

Regarding your question per se I'll let other chime in.

 

[voodooless]

If it’s a similar device to mine, it has a silent mode that one can enable at night.

You can also buy shrouds that direct the sound upwards.

 

[Nick4191]

Thank you for the replies!

 

[Nick4191]

If it’s a similar device to mine, it has a silent mode that one can enable at night.

You can also buy shrouds that direct the sound upwards.

The thing is that it's the neighbors heatpump. Maybe they are willing to use silent mode during the night?

What type of shrouds are you talking about? Do you have a concrete example of a product?

 

[Nick4191]

I'm presuming your in the States, in my country after 11pm anything over 65 DBA (measured from inside the house with windows open) is illegal and I am sure its similar in many places around the world. Check your local council regulations.

In terms of what else you can do, I would put double glazed Euro windows with the largest air gap between the two panes with one pane at least 10mm thick. Although that won't be very effective against the low rumbling noise it can mitigate it a little which might be enough, don't take my word for it though.

I'm not an expert on DBA, DBC, DB but from my understanding DBA omits/levels out the low frequencies and because the frequency reading is all low frequency content the DBA measurement is lower than the DBC and DB and most of these regulations are in DBA.

Regarding your question per se I'll let other chime in.

Yeah, will have to check local councils regulations. I hate having to take such matters up with a neighbor but such is life. I'm actually in Finland.

We already have double windows.

You got it. Most regulations are in dBA yes, there is dBC regulation in my country too though.

Thanks for replying with what you know.

 

[kemmler3D]

If it's not already on anti vibration pads, that might help a little. They are rubber/foam squares that go under the unit. You could ask your neighbor to install some. I also think a shroud / barrier would help.

 

[voodooless]

The thing is that it's the neighbors heatpump. Maybe they are willing to use silent mode during the night?

You can alway ask!

What type of shrouds are you talking about? Do you have a concrete example of a product?

Something like this:

 

[CuteStudio]

These heatpumps are becoming a menace, now in my area I sometimes hear them on new builds - at first I mistook it for someone leaving their hot-tub pumps on.
I would echo the above - if you can build any deflector or brick wall to direct the sound upwards, away from your windows, then that's the way to go. If the neighbour is reasonable they may help in your quest to stop this noise nuisance too.

After deflectors and a wall, hedging might help too, but for low frequencies you may need somethig heavier and closer to the noise source.
From what I've seen, many heatpumps are installed and adjusted very badly so they roar away continuously, soaking up electricity for very little effect - it may be that a decent engineer can bring him far more efficiency and you a lot less noise at the same time.