Are Heat Pumps Noisy? | Jez Climas

Are Heat Pumps Noisy? | Jez Climas

In this episode of Energy Unwrapped, I’m joined by Jez Climas from City Plumbing to tackle one of the most common questions from homeowners and heat pump sceptics: are heat pumps noisy? The short answer is usually no, but there is a lot more to it than that.

We get into where heat pump noise actually comes from, why some older units can be noticeably louder, how modern systems have become much quieter, and why installation quality matters just as much as the badge on the front. We also talk about the MCS noise assessment, neighbour impact, wall mounting, vibration, pipework noise and what can happen if a system is badly designed or badly sited.

A big theme throughout the episode is that most modern heat pumps are quieter than people expect, and in many homes they are actually less intrusive than the boiler systems they replace. But there are still cases where noise can become an issue, especially if the unit is poorly mounted, badly positioned, or connected to noisy internal pipework.

What we cover in this episode

• are heat pumps noisy in normal day-to-day use

• why modern heat pumps are often quieter than boilers

• the difference between compressor noise, fan noise and airflow noise

• why some older heat pumps sound worse than newer models

• how the MCS 42 dB noise rule works

• why siting, distance and neighbour position matter

• wall mounting, feet, brackets and vibration problems

• pipework noise, water velocity and squealing radiators indoors

• how servicing and maintenance can affect noise over time

• what homeowners should look for in a quiet heat pump installation

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Full Transcript

Below is the full transcript for this episode, lightly edited for readability.

Are Heat Pumps Actually Noisy?

The core question in this episode is simple, but the answer needs a bit of context. Jez explains that heat pumps can make noise, but in most real-world homes they are not especially noisy. In fact, one of the strongest points from the discussion is that many modern systems are quieter than people expect, and often quieter than the boiler setups they replace.

Why Heat Pumps Look Noisier Than They Really Are

One reason people worry about heat pump noise is visual. A heat pump is a big outdoor box with a visible fan, so it looks like it ought to make a racket. Jez makes the point that this visual impression often shapes people’s expectations before they have ever stood next to one. In practice, a well-designed modern unit can be surprisingly quiet.

Why Modern Heat Pumps Have Become Much Quieter

A useful part of the conversation is around how newer heat pumps are quieter than older ones. Jez explains that manufacturers have improved things such as vibration isolation, case design, acoustic treatment and airflow management. That means many of the latest air-to-water heat pumps are much better suited to domestic gardens than older, more air-conditioning-derived designs.

Where Heat Pump Noise Comes From

We also break down the main noise sources in an outdoor unit. The compressor is the biggest mechanical source, while the fan and the movement of air through the evaporator and front grille create their own sound too. Some of that is motor noise, some is airflow hiss, and some depends on how the air path has been designed.

Why Some Heat Pumps Are Louder Than Others

Not all heat pumps are created equal when it comes to sound. Jez explains that some older or more air-con-derived models can be much noisier, especially if they use lighter materials or have less attention paid to acoustic control. That helps explain why one homeowner might describe their heat pump as whisper quiet while another talks about rattles or case noise.

The MCS 42 dB Rule Explained

A key section of the episode looks at the MCS heat pump noise calculation and the familiar 42 dB rule. Jez explains that the assessment is used to estimate the noise impact at a neighbouring window or occupied room, taking account of sound power, reflections from nearby surfaces and distance from the receiver. It is not a perfect system, but it is the standard framework used for domestic installs.

Why Heat Pump Noise Data Can Be Hard to Compare

An interesting point from Jez is that manufacturer noise data is not always easy to compare directly. Test methods, presentation of results and real operating conditions can all vary. Heat pumps are also noisier when working harder, so one single headline figure does not always tell the full story. That is part of why real-world install quality still matters so much.

Tonal Noise, Inverter Whine and What the Calculations Miss

Not all noise is equally annoying. Jez talks about the difference between general background noise and more irritating tonal noise, such as an inverter whine. Even if the sound level is technically low, a narrow high-pitched tone can be much more noticeable and more annoying. That is one example of where simple noise calculations do not always capture the full lived experience.

Why Most Modern Heat Pumps Are Fine in Real Homes

Despite all the technical caveats, the real-world message is still reassuring. Jez’s experience is that most modern heat pumps are not causing major neighbour noise problems when installed properly. In many cases, people are surprised at how quiet they are, even when running hard. That fits with my own experience too, where my heat pump is barely noticeable near the house.

Heat Pumps vs Boilers for Everyday Noise

One of the more useful comparisons in the episode is between heat pumps and boilers. Jez makes the point that boilers have always made noise too, both inside the home and at the flue, but they have historically faced less scrutiny. In practice, many households moving to a heat pump end up with less audible heating-related noise overall, especially indoors.

Why Indoor Pumps and Hydro Boxes Can Add Noise

We also discuss indoor noise sources, particularly where the circulation pump is indoors rather than in the outdoor unit. Depending on the setup, a homeowner may hear a pump or associated components in a cupboard or plant space. That is one reason many newer systems are moving more components outdoors, keeping the inside of the house quieter.

Why Wall Mounting and Poor Bases Can Cause Vibration Issues

Another important part of the discussion is that the installation method can make a big difference. A heat pump may be quiet in itself, but if it is wall mounted badly, fixed to a resonant structure, or set on an unsuitable base, vibration can transfer into the building. That can create buzzing or structural noise that feels much worse indoors than the outdoor sound alone would suggest.

Pipework, Sleeves and Rattles Through the Wall

Noise is not only about the outdoor box. Pipework entering the house can also transmit vibration if it is not isolated properly. Jez talks about the benefit of good sleeves, lagging and flexible connections to help stop small movements and vibration being passed into the wall or the internal system.

Why Some Heat Pump Systems Make Indoor Pipe Noise

A lot of homeowner complaints about “heat pump noise” are actually about indoor water noise rather than the outdoor unit itself. High flow velocities, restrictive pipework, tight lockshield settings or poor balancing can all lead to rushing water sounds, squeals or radiator noise inside the house. That is often more about system design than the heat pump unit itself.

Why Maintenance Matters for Long-Term Heat Pump Noise

We also look at what can happen over time. Bearings can wear, fans can go out of balance, screws can loosen and cases can start to rattle. These are normal ageing risks for any rotating equipment. That means long-term servicing and maintenance may become more important as the installed base of heat pumps gets older.

Level, Stability and Long-Term Reliability

Jez also explains why a heat pump should be mounted solidly and sensibly level. A badly supported or unstable unit can put more stress on rotating parts and vibration mounts, which can affect both noise and long-term wear. There may be some tolerance in practice, but good install standards still matter.

Why Quiet Rural Installs Need Extra Thought

One especially interesting point is that an install that passes the standard MCS check may still need more thought in a very quiet rural setting. In the countryside, background noise can be much lower, so even a modest sound source can feel more noticeable. That means installers should not just rely on the number. They should also use common sense about position, direction and neighbour impact.

What Homeowners Can Do to Reduce Heat Pump Noise

By the end of the episode, the homeowner advice is fairly clear. Choose a good installer. Think carefully about siting. Avoid poor wall mounting where possible. Make sure pipework is properly supported and isolated. Check that internal flow rates and radiator balancing are sensible. And remember that if a heat pump sounds noisy, it may not be the outdoor unit itself that is the real problem.

About the Energy Unwrapped Podcast

Energy Unwrapped is my podcast about renewables, home electrification and how energy technology works in the real world. You can browse all episodes, platform links and future updates on the main Energy Unwrapped Podcast page.

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