Heat Pump Noise Levels: How Loud Are They Really?

Heat Pump Noise Levels UK: What to Expect and How to Manage It

Noise is one of the most common concerns among homeowners considering a heat pump, and one of the most common reasons neighbours object to installations. This guide explains exactly how loud heat pumps are, what the planning rules say, which models are quietest, and what you can do to minimise noise if it is a concern for your household.

How Loud Are Heat Pumps?

Air source heat pumps produce sound from two sources: the fan drawing air across the outdoor unit, and the compressor. Most modern residential units operate in the range of 40–60 dB(A) measured at 1 metre from the unit. In practice, at typical installation distances from a house or boundary (3–5 metres), this reduces to around 40–50 dB(A).

To put these numbers in context:

Sound Source	Typical Level (dB(A))	How It Sounds
Whisper / rustling leaves	30 dB(A)	Barely audible
Quiet fridge hum	40 dB(A)	Audible in a silent room
Quiet room / library	45 dB(A)	Noticeable but not intrusive
Normal conversation	60 dB(A)	Clearly audible
Busy road at 10m	70 dB(A)	Loud; requires raised voice nearby
Petrol lawn mower	90 dB(A)	Very loud; hearing protection advised

The key point is that decibels are logarithmic: a 10 dB increase represents a doubling of perceived loudness. A heat pump at 50 dB(A) is noticeably louder than a fridge at 40 dB(A), but far quieter than a normal conversation.

The Planning Rule: MCS 020

Under permitted development rules in England, an air source heat pump can be installed without a full planning application provided it meets the MCS 020 noise standard. The key requirement is:

The heat pump must not exceed 42 dB(A) at the nearest neighbour's window or door.

This is assessed by your MCS-certified installer before installation, using a calculation based on the unit's sound power level (published by the manufacturer), the distance to the nearest neighbour's relevant opening, and any intervening barriers. If the calculation shows the limit would be exceeded, permitted development rights do not apply and full planning permission is required.

In practice, most modern heat pumps installed at a reasonable distance from the boundary will pass this test — but in tightly packed terraced housing or flats, it can be a genuine constraint. Your installer should carry out this calculation before you commit to a unit.

The Quietest Heat Pump Models

Noise performance varies significantly between brands and models. Here is how the major brands compare:

Brand & Model	Noise Level	Measurement Basis	Notes
Mitsubishi Ecodan (5kW)	45 dB(A)	At 1 metre	Quietest in the mainstream market
Samsung EHS (8kW)	52 dB(A)	At 1 metre	Good for its output range
Vaillant Arotherm Plus (7kW)	54 dB(A)	At 3 metres	Strong performance at 3m; note different measurement distance
Daikin Altherma 3 (8kW)	55 dB(A)	At 1 metre	Average for the category
Grant Aerona3 (10kW)	56 dB(A)	At 1 metre	Slightly higher output contributes to level

Note: Manufacturers use different measurement distances. Always compare sound power level (Lw in dB(A)) rather than sound pressure level at a stated distance for fair comparisons. Your installer can convert these using MCS 020 methodology.

Larger heat pumps (12kW+) are typically 3–5 dB louder than smaller ones of the same model. Right-sizing your heat pump through a proper heat loss calculation is therefore important for noise as well as efficiency.

Practical Noise Reduction Measures

Siting and Positioning

Where you place the outdoor unit has the biggest impact on perceived noise. As a rule of thumb, sound reduces by approximately 6 dB for every doubling of distance. Positioning the unit:

• Away from bedrooms — especially your own or your neighbours'. Placing it at the far end of the house from sleeping areas makes a significant difference to night-time disturbance.
• Away from corners — sound reflects off walls; avoid positioning in corners or against two walls where sound can build up.
• Not directly beneath a window — noise travels upward into open windows; aim for placement at least 1 metre to the side of any frequently opened window.

Anti-Vibration Mounts

Some noise from heat pumps is transmitted as vibration through the building fabric rather than as airborne sound. Anti-vibration mounts (rubber or spring isolators placed between the unit and its mounting pad) cost £50–£150 and can reduce transmitted vibration significantly. They are a worthwhile addition for any unit mounted on a wall bracket or concrete pad attached to the building.

Acoustic Fencing or Barriers

A solid acoustic fence or planted hedge between the heat pump and the nearest neighbour's boundary can reduce noise levels by 5–10 dB(A), which is a substantial perceptible reduction. The barrier needs to be dense (solid timber or masonry, not slatted fencing) and tall enough to interrupt the direct line of sight between the unit and the neighbour's window. Specialist acoustic enclosures designed for heat pumps are also available from suppliers such as Noise Shield and SilentAir, costing £300–£800 fitted.

Note: any barrier must not restrict airflow to the unit, which needs clear access to ambient air. Manufacturers publish minimum clearance distances that must be maintained.

Addressing Neighbour Concerns

If a neighbour raises concerns about your planned heat pump installation, the best approach is to engage early and transparently:

• Share the MCS 020 noise calculation with them before installation. Showing that the unit will be below 42 dB(A) at their window is usually reassuring.
• Discuss siting options — if there is flexibility in where the unit is placed, involve them in finding the least intrusive location.
• Offer to monitor noise post-installation — modern heat pumps can be operated in a night quiet mode (typically 3–6 dB quieter but with some efficiency reduction) if noise proves to be an issue after installation.

If a neighbour formally objects after installation and claims statutory noise nuisance, the local council's environmental health team will assess the noise against the MCS 020 standard. Provided your installer carried out the calculation correctly and the unit is operating within specification, complaints are rarely upheld.

Key Takeaways

• Heat pumps typically produce 40–60 dB(A) — roughly equivalent to a quiet room to a normal conversation
• The MCS 020 planning rule limits noise to 42 dB(A) at a neighbour's window
• The quietest mainstream model is the Mitsubishi Ecodan, reaching 45 dB(A) at 1 metre for smaller output units
• Practical steps — siting away from bedrooms, anti-vibration mounts, acoustic barriers — can reduce noise meaningfully
• Engage neighbours early with data rather than reassurances

For a full comparison of heat pump models including efficiency and cost data, see our guide to the best heat pumps in the UK. If you are weighing up whether the overall package makes sense for your home, read our honest assessment of whether heat pumps are worth it.