Are heat pumps really noisy? What you’ll actually hear at home – UK Times

For many of us thinking about getting a heat pump, the main consideration is: what will it be like to live with?

Cost, of course, matters, as does efficiency. And so does the question of whether a heat pump can keep a British home warm on a damp January morning. But for many homeowners, there is another, quieter concern. If a heat pump sits outside the house and uses a fan to draw warmth from the air, does that mean swapping the familiar hush of a gas boiler for a constant outdoor hum?

It’s a reasonable question. We know what boilers sound like: a click, a whirr, a whoosh from a cupboard or utility room. A heat pump is different. The main unit usually sits outside, and while modern systems are designed to run quietly, they are not completely silent. The better question is not whether a heat pump makes any sound at all, but whether that sound is likely to be noticeable, disruptive or annoying to neighbours.

What does a heat pump actually sound like?

An air source heat pump has an outdoor unit with a fan and a compressor. The fan pulls air across the unit, while the compressor helps raise the temperature of the refrigerant so that heat can be transferred into the home’s heating and hot water system.

In normal operation, the sound is usually closer to airflow and a low mechanical hum than the firing noise of a boiler. It also tends to be steadier. A gas boiler may kick in, heat water quickly and switch off again; a heat pump is more likely to run for longer periods at lower intensity, keeping the home at a more stable temperature.

That steady operation can actually be part of the reason people notice heat pumps less once they are installed. Instead of an appliance repeatedly starting and stopping indoors, the outdoor unit becomes part of the background soundscape. However, it can be more noticeable at night, in very quiet streets or when the unit is placed near a bedroom window, patio, alleyway or neighbouring property.

According to Octopus Energy, heat pumps are generally around 40–60 decibels, which it compares with the sound of a fridge freezer or gas boiler. Because the unit is outside, Octopus says the sound should not be too noticeable for most people.

How loud is 40-60 decibels?

Decibel comparisons are helpful, but they can also be misleading if they are treated too literally. A modern fridge, a quiet conversation, rain against a window and distant traffic may sit in a similar broad range, but they don’t feel the same to the ear.

As a rough guide, a quiet library is often around 40dB, a fridge may sit around 40-50dB, and a normal conversation is commonly around 60dB. On paper, that puts many heat pumps in familiar household territory. But what matters in practice is not just the sound level produced by the unit. It’s also where the sound travels, what it bounces off, and where people are when they hear it.

This is where heat pump specifications can be confusing. Manufacturers often list the “sound power level” of a unit, which describes the sound energy the appliance produces. What a homeowner or neighbour hears is the sound pressure level, which depends on distance, surfaces, barriers and the surrounding environment.

For example, Octopus’s Cosy heat pump range lists sound power levels of 58dB(A) for the Cosy 6, 56dB(A) for the Cosy 9 and 60dB(A) for the Cosy 12. That doesn’t mean a neighbour standing several metres away will necessarily hear that exact figure. Sound falls with distance, and walls, fences, planting and careful positioning can all affect how noticeable it is.

Why installation matters as much as the model

A good heat pump installation isn’t simply a case of choosing a unit and finding the nearest patch of wall. Placement can make all the difference between a heat pump that fades into the background and one that becomes unnecessarily irritating.

A unit squeezed into a narrow, hard-sided passage may sound louder because sound reflects off the walls, while a heat pump installed close to a bedroom window may be more noticeable at night, even if it is operating within permitted limits. A unit placed on an unstable base or without proper vibration control may create more mechanical noise than it should.

Sizing is also key. A heat pump should be matched to the home’s heat demand. If the unit is poorly specified, badly installed or forced to work harder than necessary, it may be more noticeable to your ear. In cold weather, the fan and compressor may work harder as the system extracts heat from colder air, and occasional defrost cycles may briefly change the sound.

None of this means heat pumps are inherently noisy. It means the survey and installation process plays a big part in how much noise you’ll hear. A reputable installer should consider where the unit will sit, how close it is to neighbouring windows, whether there are reflective surfaces nearby, how vibration will be controlled and whether the proposed installation meets the relevant noise rules.

Will a heat pump annoy the neighbours?

Neighbour noise is one of the biggest worries around heat pumps, especially for terraces, semi-detached homes and properties with smaller gardens. It is also one of the reasons planning rules have attracted so much attention.

In England, the rules changed in 2025 to make many air source heat pump installations easier. The previous one-metre boundary restriction was removed, giving installers more flexibility over where units can be placed. However, that doesn’t mean heat pumps can simply be installed anywhere without considering their noise.

The MCS guidance on new permitted development rules says air source heat pump installations under permitted development must comply with MCS 020, the planning standard used to assess noise. The Planning Portal also states that permitted development applies only if the installation complies with the relevant MCS planning standard or equivalent standards.

In practice, this means the installer should assess the likely sound level at the nearest relevant neighbouring windows or assessment points. If the proposed location or model doesn’t meet the standard, you may need a different design, a different location, or perhaps planning permission.

For homeowners, the key is to raise noise early in the process, while there is still time to adjust the design or location.

What should you ask before installation?

If you’re worried about noise, the best time to raise it is before the heat pump is installed, not after. A good installer should be able to explain why a particular location has been chosen and how the sound level has been assessed.

Before agreeing to an installation, ask:

It’s also worth asking what would happen if the first proposed location isn’t suitable. In some homes, moving the unit by even a small distance, avoiding a narrow side passage or choosing a quieter model can make a meaningful difference.

So, are heat pumps really noisy?

Heat pumps are not silent. They have a fan, they have a compressor, and these types of moving parts all make a sound. But the idea that a heat pump inevitably turns a quiet home into a noisy one is too simplistic.

For most households, a modern, well-installed heat pump should be a background sound rather than a daily irritation. A heat pump placed thoughtfully, sized correctly and assessed properly for noise should not dominate your garden, bedroom or neighbourly relations.

The best advice for homeowners is to treat noise as part of the design conversation from the start. Ask where the unit will go. Ask how loud it is expected to be at your property and your neighbour’s property. Ask whether the installation meets the relevant planning standard. And if the first proposed location feels too close to a bedroom, patio or boundary, ask whether there is a better option.

A quiet home isn’t necessarily one where every appliance is silent, but one where the technology fades into the background. And with the right installation, this is what a heat pump should do.