Because heat pumps come in all shapes and sizes, the sound and volume of noise they make varies between models and manufacturers. Fortunately, due to government regulations (see do you need planning permission for a heat pump), most modern air source heat pumps can work a lot quieter than older models.
What does an air source heat pump sound like?
The clip above shows 3 different air source heat pump installations working at different speeds. In the first clip, 3 Vaillant air source heat pumps are all working simultaneously in a mild climate (approx. 6oC). The second is of a single Daikin unit at approx. 3oC, and the third is in colder conditions (December, -6oC). This video was filmed on an iPhone 7 at a distance of 1 – 3 metres.
As you can probably tell, modern air source heat pumps shouldn’t make more than a low whirring sound providing they’re working properly.
The volume of noise also depends on how much work the heat pump is doing – the greater the work load, the louder the heat pump will be. This is down to the speed of the fan that draws warm air into the compressor (see how does a heat pump work).
Noise regulations during installation
Noise pollution is calculated during the design stage of the heat pump installation to avoid disturbing your neighbours. The outdoor unit should be sited as far away from the neighbouring property as possible, and it’s also a good idea not to site the box directly beneath any windows.
Most modern heat pumps are built in a way that give off as little noise as possible to avoid putting the customers through the hassle of applying for planning permission. These newer models tend to be better designed, with thicker chassis and quieter fans.
If the noise pollution is 42 decibels or more from the nearest neighbouring property, the installation would need planning permission. However, it’s down to your installer to ensure that the heat pump is below the noise pollution levels of Permitted Development rights.
To put this into perspective, take a look at the table below:
Noise level (decibels)
|Whispering / rustling leaves||20|
|Quiet rural area||30|
|Library / bird calls||40|
|Heat pump noise limit (MCS)
|Conversation at home||50|
|Conversation in an office or restaurant||60|
|Alarm clock / dishwasher||80|
NB: there are a number of videos online of faulty heat pumps making a alarming racket, but don’t let this put you off. Most modern heat pumps are only audible from a few metres away, as in the video above. If your heat pump starts making more noise than usual, get in touch with the contractor who installed the heat pump.
Noise from ground source heat pump
In contrast, ground source heat pumps sound not dissimilar to a dishwasher. They also generally make less noise because there’s no fan component and the heat source is warmer, so there’s less strain on the compressor. Furthermore, the main unit of sits inside your home, so your neighbours can rest easy.
However, unlike a dishwasher, you may want to keep the heating on overnight if it’s a particularly cold evening. Keep this in mind when you’re deciding where to fit the ground source heat pump – the vibrations can be a bother if you’re in a room adjacent to or above it. One solution is to get some antivibration feet or pads, or if you’re a particularly light sleeper, to install sound proofing around the system.