Air source heat pumps have many benefits, making them a popular upgrade in domestic and commercial properties.
However, air source heat pumps sit outside and can have one or more fans working throughout the day and so their general noise level is a valid concern—especially in domestic environments. So, are air source heat pumps noisy?
An air source heat pump can be relatively noisy during operation but can vary depending on the age and model of heat pump, as well as the current temperature. As air source heat pumps can be expected to make some level of noise, they’re typically installed in a more secluded location.
Our air source heat pump can be relatively noisy when you’re up close to it and it’s working hard in colder temperatures, but the noise levels reduce significantly as you move away.
An air source heat pump will always make some level of noise during operation, but we discuss further in this article why they make noise and what you can do to help reduce the noise levels overall created by them.
Air source heat pumps (ASHP) make some noise due to their components. They typically contain an evaporator, an expansion valve, a condenser, and a compressor.
The compressor and the fan(s) are responsible for the noise while an ASHP is operating.
The air and pressure flow, as well as the fan speed and model, are all factors that can determine how noisy a heat pump would be.
Our air source heat pump is a dual fan unit sized appropriately for our 5-bedroom house. The fans are required in order to force enough fresh air over refrigerant flowing through the unit for heat energy to be captured.
There’s also a compressor within this outdoor air source heat pump unit that compresses the refrigerant to higher pressures. This in turn increases the temperature of the refrigerant, therefore allowing us to capture more heat for use in our central heating system and domestic hot water when that heat is transferred to the hot water tank inside our home.
Our air source heat pump isn’t always operating but when it does there is some level of noise generated.
Air source heat pumps will also need to work harder in colder temperatures because the temperature difference between the air inside and outside of a home will be greater.
In colder temperatures, our heat pump will be working harder and can be operating for longer periods of time, and can be noisier as a result.
A modern air source heat pump in good working condition shouldn’t make more than a low buzzing sound similar to what you’d expect from an air conditioner. However, noise levels can increase the closer you are to the unit or when the heat pump is having to work harder.
Below is a video of our heat pump working in December when it’s relatively cold.
Our heat pump could be considered quite noisy, but we’re stood right in front the fans near to the unit and in cold temperature when it’s working harder to extract heat from the air.
Here’s a short video that captures the sound from an air source heat pump from another perspective:
There are ways to help reduce the noise from an air source heat pump, which we discuss further in this article.
Moving away from an air source heat pump, especially out of the way of the fans, will decrease the noise you can hear from one drastically.
As mentioned previously, the harder an air source heat pump must work (such as in colder temperatures), the louder it can be as it uses up more energy to generate the same desired internal heating temperatures.
Therefore, expect an air source heat pump to be quieter in the warmer months when the temperature difference between the inside and outside air isn’t as extreme.
You’ll also find an ASHP won’t be on as much during warmer months when heating isn’t required (but still potentially being used for domestic hot water), and an external heat pump unit makes no noise when it’s not on.
You can expect an air source heat pump to generate between 40 and 60 decibels of noise when up close.
As an example, the noise levels for our own air source heat pump are outlined below:
The sound pressure level (SPL) of our heat pump in heating mode is 53dB and the sound power level (PWL) is 69bB, making it slightly noisier than the average, but it is a larger unit.
When installing a heat pump, you’ll need to pay attention to your surroundings to ensure the noise isn’t too loud for your neighbors.
The outdoor portion of the pump should be kept far enough away from the nearest property, and you should avoid installing it under any window.
You may need to apply for planning permission if the heat pump noise is more than 42 decibels when measured from your neighbor’s property. Expert installers know how to position the units to ensure you don’t go above the limit. Modern designs also come with quieter fans and thicker encasements to keep the noise levels as low as possible.
Our air source heat pump is installed down the side of the house adjacent to the internal garage and so away from any windows and bedrooms. It’s also located far enough away from the neighboring property and hidden behind a fence.
See our article on air source heat pump installation requirements for more information.
If you find an example of an air source heat pump making too much noise, it’s likely a defective or poorly installed unit. It may also be a very old model. If your heat pump suddenly becomes noisier than usual a few weeks after installation, call in a contractor for some checks.
To ensure the noise from your air source heat pump is at its lowest, here are some approaches to consider:
You should make sure the outdoor unit is installed in an optimal location. That way, you can reduce the perception of noise for both yourself and your neighbor. Avoid installing them below any windows in your home as the low hum could interrupt your rest.
Similarly, it shouldn’t be positioned towards your neighbor’s property. If your neighbor’s property borders yours from behind, consider placing your heat pump’s outdoor unit by the sides of your home.
See our article on where to install an air source heat pump for more information.
You should also place your unit in a secluded but open area out of direct sunlight to ensure the fan won’t have to work too hard to draw in heat from the air, which could increase noise.
Acoustic enclosures are designed to surround outdoor mechanical equipment such as air source heat pumps. They dampen the sound to ensure you’re not exceeding planning restrictions or to make the unit generally quieter.
They achieve noise reduction without inhibiting airflow.
The best units have an unobtrusive design, and they aren’t too hard to install. They also feature extras like anti-vibration mounts which reduce the consistent humming sounds that may interfere with your day-to-day living around the heat pump installation.
You can find compatible options for all kinds of heat pump systems in the market currently, so talk to your installer about one. Acoustic enclosures also don’t look out of place around your installation, as you’re sure to find one that fits your heat pump’s finish.
Whether you choose an enclosure or not, an installer will typically fix air source heat pumps to the ground on anti-vibration mounts, such as ours is shown below, to help reduce noise from vibration.
Ground source heat pumps aren’t completely quiet. They make some noise, but they’re often quieter compared to air source heat pumps overall. While an air source heat pump can reach 60 decibels, a ground source heat pump will max out at around 40 decibels.
A ground source heat pump can be quieter in general compared to air source heat pumps because it doesn’t have to work too hard to pull heat from the ground.
The compressors on these units aren’t as powerful for this reason. Since the heat pump doesn’t need to operate at full throttle, it stays quieter overall.
The average ground source heat pump is just about as loud as your domestic refrigerator. Most importantly, the noisy elements can be inside your home, so there can be a lower noise risk for all parties.
However, ground source heat pumps also require significantly more land than air source heat pumps, making ground source heat pumps unsuitable for many homes even if they can be quieter.
If you’re looking to choose between an air or ground source heat pump, your decision shouldn’t be influenced by noise levels alone. Factors such as overall efficiency and possible energy savings are typically more important.
Air source heat pumps will make some noise, but the loudness can often be negligible if you’re not standing directly next to the outdoor unit or in front of operating fans.
Larger units that are working harder in colder temperatures can be noisier than smaller units working in warmer temperatures.
Air source heat pumps are typically installed away from windows and bedrooms, and far enough away from neighboring properties to ensure that noise levels remain minimal for all.