Busting the myths surrounding heat pumps

◄ Back to all articles

Heat pumps are more in demand than ever before: they supply heat efficiently and are environmentally friendly. Nevertheless, the more popular they become, the more quickly myths spread concerning their characteristics and operation. In this article, we’re going to straighten things up.

1. Heat pumps are too expensive

A suitably designed and professionally installed heat pump which is operated correctly is more cost-effective across its entire service life than any traditional heat generator. A heat pump may cost up to 50% more than a gas boiler, but the initial investment is recouped after just a short period of time, as the heat pump pays for itself due to the low operating costs.

The operating costs depend on the system temperatures: low system temperatures mean low operating costs. Underfloor heating, for example, facilitates low system temperatures. The ideal flow temperature for this kind of system is between 28 and 35°C, depending on the type of building. Fan convectors may also be suitable for heat pump operation. As heat pumps work with renewable forms of energy, many countries are willing to provide subsidies to support this.

2. Heat pumps supply little heat when outside temperatures are very low


Today, the latest generation of air/water heat pumps reliably provide heat when temperatures are as low as -20°C. If the level of heat still isn’t quite sufficient, electrical heating is temporarily switched on when outside temperatures are extremely low. This supplies the required level of heat when combined with the heat pump.

Geothermal heat pumps (such as the Hoval Thermalia®) use heat taken from the earth. As an example, they can use the groundwater found in areas where water is abundant directly below the earth’s surface. In contrast to the outside air used by air/water heat pumps, groundwater temperatures remain relatively constant throughout the entire year. If groundwater temperatures are between 9 and 12°C on average, groundwater heat pumps (such as the Hoval Thermalia®) can be operated very efficiently.

3. Heat pumps are only used for heating purposes

The term “heat pump” is not actually ideal, as heat pumps are also able to work the other way round and cool rooms throughout the summer months. They can therefore be described as reversible, and this method of cooling a room – ideally with fan convectors – is even recommended. However, the connection pipes carrying water must be very well insulated to prevent condensation.

4. Heat pumps are very loud

When heat pumps first came on the scene – some years ago now – their external units reached a noise level of around 76 dB. This has since dramatically reduced. The external unit of a Hoval Belaria® air/water heat pump now produces noise levels of 54 to 57 dB, depending on the power output. The sound pressure levels – the noise actually perceived by the human ear – are even lower: they reach between 35 and 38 dB at a distance of 5 m and between 29 and 32 dB at a distance of 10 m. These values apply when the external unit is located on one side of the building. They are reduced by 3 dB if the appliance is encased in a sound-absorbent material. If it is set up in a corner of the building, the sound pressure values increase by 3 dB. The fan and compressor are the sources of noise. However, compressor technology has also progressed significantly over the past few years. Scroll compressors, in particular, are much quieter when compared to the pistons that were originally used.

So what can these noise levels be compared to? The following list illustrates just how quietly heat pumps work today:

0 dB: You will only find an atmosphere this quiet in an acoustic laboratory.

10 dB: This level of silence – which is still unusually low – can be found in a recording studio.

20 dB: A quiet garden with leaves rustling occasionally.

30 dB: This level would be measured in a bedroom, for example.

35 dB: The value is about this high in a quiet residential building.

40 dB: Quiet voices in a library.   

50 dB: The sound of the rain.

60 dB: A car driving past.

5. Heat pumps are only suitable for new buildings

Heat pumps can also provide an excellent solution in cases where existing buildings are being restored. The most important consideration is selecting the right type and capacity. It is also important to bear in mind the heat distributors (in underfloor heating, for example) and their operating temperatures, the building insulation, and the availability of a suitable heat source for the heat pump.

With its external and internal units, an air/water heat pump is very similar to an air conditioning unit. This kind of heat pump is more suitable for residential buildings, while a geothermal heat pump is best suited to new buildings, as drilling into the earth is required in order for heat exchange to take place. Old buildings must first be assessed for sources of heat loss resulting from insufficient insulation or leaking window seals. These may indirectly impair the efficiency of the heat pump.

6. Heat pumps take up a lot of space

Geothermal heat pumps require about the same amount of space as a gas condensing boiler. Both require a boiler room.

The Hoval Belaria® SRM (4-16) air/water heat pump features an external unit measuring 80 cm long and 73 cm wide, for example. The internal unit only measures 81 x 38 cm.

7. Heat pumps require regular inspections

Compared to traditional boilers, which need to be cleaned regularly, heat pumps require little maintenance. Nevertheless, we recommend that you have your heat pump checked regularly by Hoval Service to ensure that it continues to work efficiently and remains a source of cosy heat.

Alexandra Dragoi

More information


A cookie is a small piece of text sent to your browser by a website that you visit. It helps the website to remember information about your visit, like your preferred language and other settings. That can make your next visit easier and the site more useful to you. Cookies play an important role. Without them, using the web would be a much more frustrating experience.

Terms of use

Privacy policy

Cookies help us deliver our services. By using our services, you agree to our use of cookies.