How a Heat Pump can Protect the Environment and Your Neighbours

November 4, 2021
  1. Only air-to-water heat pumps can be installed outdoors
  2. The first air-water heat pumps were still really loud
  3. Five tips: How to avoid trouble with your neighbours
  4. Pretty smart: powerful and whisper-quiet
  5. Today, there is nothing to be said against an externally installed heat pump


In the long term, heat pumps are cheaper than other heating systems, energy-efficient, resource-saving and environmentally friendly. That is why they are a sensible alternative to older heating systems such as oil heating in the long term. With our energy calculator you can, for example, calculate the investment costs and subsidies and simulate how a heat pump will affect your energy consumption and costs. However, the air-to-water heat pumps, which are by far the most widespread in Switzerland, are comparatively noisy. To heat an average single-family house, up to 6000 cubic metres of air per hour must flow through a fan into the evaporator. You can hear this if you are standing nearby. How can you protect yourself and your neighbours from the noise?

Houzy Advice

Good to know

In our article "Heat Pump: Costs, Advantages and Subsidies" we have summarised in an easy-to-understand way what you as a homeowner should know about heat pumps.


Only air-to-water heat pumps can be installed outdoors

Air-to-water heat pumps are cheaper than other heat pumps because there is no need to lay a geothermal heat collector or drill a hole for the ground probe. An air-to-water heat pump draws in air and transfers it to a heat exchanger. A refrigerant circulates in the heat exchanger, which changes its state of aggregation at low temperatures and evaporates. This refrigerant vapour is compressed by a compressor and heated to a temperature that can be used for heating and hot water preparation. Only air-to-water heat pumps can be installed indoors and outdoors. Many homeowners have them installed outside to save space in the basement: the compact heat pump is protected in a weatherproof housing and pumps the heat into the storage tank via heat-insulated pipes in the floor. When renovating older properties, it is also easier and cheaper to install a heat pump outside instead of inside.

Older Heat Pump
In the past, air-to-water heat pumps were not only loud, but huge and not a pretty sight.

The first air-water heat pumps were still really loud

Since the beginning of the 2000s, air-to-water heat pumps have been increasingly installed outside. At that time, they were still really loud at 76 decibels. The compressor and the fan were mainly responsible for this. In the meantime, the technology has developed considerably, especially the compressors with the change from piston to compressor. That's why the average noise level has dropped to 50 to 60 decibels, depending on the unit and its output. That is louder than birdsong, but quieter than a conversation between friends and comparable to a refrigerator. How loud a heat pump really can be found on its product data sheet, which you can usually find on the manufacturer's website. The volume is given in dB(A). dB stands for decibel and is the unit of measurement for the pressure that the sound waves exert on our eardrums. The letter in brackets, usually an A, indicates the pitch or frequency at which the volume was measured.

Houzy Advice

Good to know

The temperature has a significant influence on the noise level, because a heat pump has to work harder at cold temperatures and is therefore louder in winter than in summer.

Heat Pump

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Five tips: How to avoid trouble with your neighbours

With the choice of location, you can reduce the noise level of the air-to-water heat pump. This is how you protect yourself, your family and the peace in the neighbourhood in the long term: Install the heat pump ...

  1. ... at least three metres from the neighbouring property, but close to your house, to minimise heat loss through excessively long pipes in the cold ground.

  2. ... so that the fan is not visible through the windows of the neighbouring houses and your house, this avoids or minimises disturbances due to operating noise.

  3. ... on the usually louder street side of the property, then the passing cars (60 decibels) or motorbikes drown out the sounds of the compressor and fan.

  4. ... not between two walls, because they reflect and amplify the noise.

  5. ... without obstacles in the exhaust air flow, so that no turbulence occurs.

Houzy Advice

Good to know

Having the heat pump planned and installed by professionals is cheaper than having to move it later, change the discharge direction or retrofit vibration dampers. A sound insulation bonnet is only a stopgap solution and costs a lot.

Pretty smart: powerful and whisper-quiet

The technology has improved massively in recent years. Modern air-to-water heat pumps are more powerful and yet whisper quiet. Innovative machines such as the AEROTOP® SG from Elco, for example, are quieter than comparable air-to-water heat pumps, without compromising on performance. In reduced night mode, the heat pump is as quiet as voices in a library from one metre away and as quiet as a whisper from four metres away. The engineers and technicians have achieved this with three intelligent improvements:

  • The oversized evaporator with only two rows of pipes allows slower air flow with lower pressure losses.
  • The fan rotates much slower, so the air is hardly accelerated, which significantly reduces airborne noise.
  • The compressor is triple-suspended with vibration dampers independently of the housing, does not vibrate and does not cause structure-borne noise.

Innovative air-to-water heat pumps like the AEROTOP® SG models from Elco are barely audible from a few metres away. They comply with all noise protection guidelines and ensure more peace and quiet in the neighbourhood. What's more, they look good and fit in just as well with modern new buildings as they do with renovated old buildings.

Today, there is nothing to be said against an externally installed heat pump

Unlike in the past, noise is no longer an issue when you want to install an air-to-water heat pump in your garden. Heat pumps today are so quiet that your neighbours can hardly hear the noise of the evaporator, fan or compressor from three metres away. When choosing a heat pump, pay attention to the volume (in the product data sheet) and follow the tips in our article when choosing a location. Then you can also relieve the environment and save energy costs with an air-water heat pump installed outside without annoying your neighbours.

Are you considering replacing your heating system with an environmentally friendly and cost-efficient heat pump? Be sure to get advice from professionals.

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