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Are heat pumps noisy? It is one of the few questions here with a real number behind it, and on a Devon plot the position decides the rest. In England an air source heat pump has to calculate at or below 37 decibels one metre outside habitable room windows of neighbouring properties, to be fitted under permitted development.
Key Takeaways
- England’s permitted development limit is 37 dB, calculated a metre outside habitable room windows of neighbouring properties.
- The Ideal Logic Air range publishes a sound power level of 52 dB(A) at 4 and 5 kW and 55 dB(A) at 8 and 10 kW.
- Sound power is a lab rating. Distance, nearby hard surfaces and any solid barrier decide the level that reaches a window.
- On a Devon plot, the standard’s formula puts one unit at 32 dB eight metres from a neighbour’s window and over the limit tucked into a corner.
- A Freedom of Information study reported by Nesta found 124 councils logged no heat pump noise complaints between 2020 and 2023.
- Your installer has to hand you a copy of the completed sound calculation for your own property.
The worry underneath is usually social rather than technical. Nobody wants the machine the neighbours end up mentioning, and in a small Devon village that travels. This post covers what a published decibel figure means, where the 37 dB limit applies, why the position moves it more than the model does, and what happens when one does sound wrong.
Are Heat Pumps Noisy? What One Actually Sounds Like in a Garden
Two different measurements get quoted for heat pumps and they are not the same thing. Sound power is the total sound energy the machine puts out, measured in a lab to EN 12102-1. Sound pressure is what someone standing in a particular spot hears, and it drops off with distance.
The Ideal Logic Air range, which we fit most often, publishes a sound power level of 52 dB(A) at 4 and 5 kW and 55 dB(A) at 8 and 10 kW. The 8 kW unit carries Quiet Mark certification. That 55 is an input to the sound calculation, and what lands at your neighbour’s window comes out lower.
How far apart those two numbers sit is worth seeing, and the MCS standard’s own worked example shows it with a unit louder than any of them.
The worked example in the MCS standard
60 dB(A)
The unit in the worked example, louder than anything in the Logic Air range
32.0 dB(A)
What arrives at the window, inside the 37 dB limit
The 37 dB Limit Every Permitted Development Install Has to Pass
The standard is MCS 020 a), the sound calculation named in the permitted development rules for England. It sets a limit of 37 dB LAeq over five minutes at what it calls the assessment position, which is a point one metre outside the centre of any door or window to a habitable room of a neighbouring property.
Where the 37 dB is measured
37 dB
LAeq over five minutes, at the assessment position outside a neighbour’s habitable room.
The standard asks for every relevant window on every side, closest or not, so James works each position round a Devon plot and checks the same calculation on the installs he audits for NAPIT.
You will still see 42 dB quoted in articles written before the rules changed. Since 29 May 2026 the MCS 020 a) route is the only one accepted in England. Scotland, Wales and Northern Ireland have their own rules.
Where the Unit Goes Decides More Than Which Unit You Buy
Three things move the number at the window: how many hard surfaces sit within a metre of the unit, how far it stands from that window, and whether anything solid blocks the line of sight. Run a 10 kW Logic Air through the standard’s formula at its published 55 dB(A) and watch the position do the work.
Worked example: one 10 kW Logic Air at 55 dB(A), four positions
About 6 dB
Doubling the distance from the window, from any of those positions
Up to 10 dB
A real barrier, solid and gap-free, between the unit and the window
Nothing
Hedging and trellis, which count for nothing in the calculation
Ground alone counts as one reflecting surface, ground plus a wall two, and a corner between two walls three. Those figures are the standard’s arithmetic on a published number, worked for example positions. Your own plot gets its own calculation. Position is part of how we design an air source heat pump installation.
Planning Rules, Neighbours and the Paperwork You Should Be Handed
In England most installations go in under permitted development, which comes with its own conditions.
Permitted development in England: the conditions
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Size: up to 1.5 cubic metres That is the outdoor unit, with its housing included.
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Number: two on a detached house Any other house is allowed one.
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Placement: not on a pitched roof Nothing goes on a pitched roof under permitted development.
Then come the properties where it stops. A listed building gets nothing under permitted development. In a conservation area the unit cannot go on a wall or roof fronting a highway. Councils can withdraw these rights street by street too. Older Devon properties bring their own constraints, which we cover in our guide to heat pumps in old houses.
The paperwork is the part homeowners rarely ask for. The installer has to keep one copy of the completed sound calculation and give another copy to you. James works as a freelance MCS assessor for NAPIT, auditing other installers’ finished heat pump work, so that sheet is something he checks on other jobs as well as producing on his own.
When a Heat Pump Does Sound Wrong, and What Usually Causes It
Genuine noise complaints are rare. A study of Freedom of Information requests, reported by Nesta, found 124 councils recorded no heat pump noise complaints at all between 2020 and 2023, with another 42 logging a single one each. A Nesta survey found 85% of owners satisfied with the noise.
The one sound that is normal
- When Cold, damp weather, while the outdoor coil clears frost
- What you hear The fan note changes for a few minutes
- Quiet mode A bonus at night, since its figure is banned from the calculation
What the bad ones share
- Vibration A unit bracketed onto a house wall passes it into the structure
- Siting Placed for pipework convenience, nearer a window than needed
- Servicing A machine years overdue a service will let you know
Bracketing passes vibration into the house, so a solid base on the ground is the safer choice. The defrost cycle is covered in our post on how heat pumps run through winter.
How Loud a Heat Pump Would Be Where You Live in Devon
General answers stop being useful at this point, because the geometry of your plot decides the result. On a town plot in somewhere like Budleigh Salterton, the nearest neighbouring window might be five or six metres from the only sensible unit position. On a lane outside Ottery St Mary it can be forty metres with a barn in between.
How the position and the sound figure get worked out
Walk the plot
At the free home assessment James walks the plot and looks at where the pipe run can go.
Settle the position
He works out where the unit can reasonably stand before any model is written down.
Calculate afterwards
The sound calculation comes afterwards, worked from the position he settles on.
Occasionally the honest answer is that a plot is too tight for the position the customer had in mind. It is unusual, and it is better heard at the first visit than after a unit has been ordered.
Frequently Asked Questions
Not at the levels people expect. In England an air source heat pump has to calculate at 37 dB or lower one metre outside a neighbour’s habitable room window before it can be installed under permitted development.
Book my free home assessmentManufacturers publish a sound power level, which is a lab figure rather than what you hear. The Ideal Logic Air range publishes 52 dB(A) at 4 and 5 kW and 55 dB(A) at 8 and 10 kW.
Book my free home assessmentIn England the permitted development limit is 37 dB at the assessment position, set by the MCS 020 a) standard. Scotland, Wales and Northern Ireland have their own rules.
Book my free home assessmentIt should not. The limit is set at a neighbour’s window, and your own bedroom window is part of the same siting decision. Position and a solid barrier do most of the work.
Book my free home assessmentA neighbour cannot object to a compliant permitted development installation the way they could to a planning application, but a council can still act if a specific installation causes a statutory nuisance.
Book my free home assessmentThere is no fixed distance any more. The one metre boundary rule was dropped in May 2025, so a unit can sit near a fence provided the sound calculation still comes in at or below 37 dB.
Book my free home assessmentFind Out What the Number Would Be at Your Own Boundary
The noise question turns specific once you look at one property: where can the unit stand, how far is that from the nearest window next door, and what sits in between. That gets measured at the free home assessment, which James does himself, and it comes with a fixed estimate on the spot.
Book my free home assessmentPrefer to talk it through first? Ring 01395 202030. James answers, and he is the person who will price the job.
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“After comparing several quotes and gathering details I decided to go with Eco Pro after speaking with James and couldn’t be happier. Their design was really detailed, explained clearly and the heat pump works perfectly.”
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