Neighbour installs 5 heat pumps 3 m from my bedrooms

[rroyal]

My house is facing north, a small garden, and 3 meters away there's the neighbour's house brick wall. Neighbour runs a small B&B hotel, has just completed architecturally designed alterations and installed 5 rather large heat pumps side-by-side on his south wall. The heatpumps will be used only for A/C in summer, he says - not for heating. So from my tiny garden, lounge and from 2 bedrooms in my house, I will see and hear these heatpumps.

Even if the heatpumps are hidden from sight with a treillis or a wall, it's still a lot of decibels!

I rang the City Council and been told that there are no rules about proximity of heatpumps. (Strange?) But there are noise regulations, which state that the maximum noise level I should perceive is 40dB at night and 60dB during the day.

I understand that each heatpump is rated at 45dB. So, how many dB are 5 heatpumps likely to emit 3 meters away?

What would you do?

[artemis]

You could ask the suppliers.

When they are all running at once ask the noise control folk at the council to measure the levels.

[flyernzl]

You can download a decibel meter for you smartphone and take a reading with that.
Possibly not incredibly accurate, but would give you a start.

[PTcruza]

Hi there rroyal,

Hmmm, not a nice situation.

Regarding noise levels, you need the distance data as well. Some things are rated at 1 metre, others (like a lawnmower or a diesel generator) might be rated at 7 metres. Also, it's not simple addition because it's a logarithmic scale. All units together might only generate 60bB, but it's still gonna be annoying on a hot summer night. Would be much better if they were only for heating.

In terms of what you can do, I don't know if this is true, but I have been told that the Fencing Rules (2 metre or 2.5 metre height limits) are virtually open if a fence is erected for noise control purposes....

That might be the easiest solution! Use corrugated iron, facing out, built just inside your property! (Corrugated will stop the sound far better than wood. In fact, it will probably reflect it all over his property!) I understand the Fencing Act and therefore the Courts have no jurisdiction over non-boundary fences.

[Bob Kane]

I understand that each heatpump is rated at 45dB. So, how many dB are 5 heatpumps likely to emit 3 meters away?

If one heatpump is 45dB then two heatpumps will be 48dB and four heatpumps will be 51dB.
The fifth heatpump might be another 1dB giving a total of approx 52dB.
NB I think that is how dBs work.

[PTcruza]

If one heatpump is 45dB then two heatpumps will be 48dB and four heatpumps will be 51dB.
The fifth heatpump might be another 1dB giving a total of approx 52dB.
NB I think that is how dBs work.

Yes, I think that's right - each time the Noise Power doubles, the dB level increases by approximately 3dB.

So, 1 + 1 = double => +3dB
Then, 2 + 2 = double again => + another 3dB
Plus one more - yes, maybe another 1dB.

But I say you still need to know the Distance the 45dB figure applies to, to work out the level at 3 metres.

Noise Power is another Inverse Square law, so double the distance => 1/4 the Power.

If it's 45dB at 1 metre, then depending how the 5 units are "stacked" or "lined up", at 3 metres you might get 47 or 48dB...

Some foliage (thin trees trimmed to suit your view) between might be enough to muffle it sufficiently.

[rroyal]

If one heatpump is 45dB then two heatpumps will be 48dB and four heatpumps will be 51dB.
The fifth heatpump might be another 1dB giving a total of approx 52dB.
NB I think that is how dBs work.

Thanks. That's useful.

[Meehole]

Hmmm maybe just play some loud head banging music when it's a full house? Lawn mower cranked up on Sunday morning (even if no lawn to mow) B & B might get a few bad reviews....