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Heat pump volume: know limits and tips for reduction

The popular heating system of the heat pump plays a decisive role in the current energy turnaround, as it does not require fossil fuels to provide sufficient heat for heating and the preparation of hot water. When deciding on a purchase and for planning purposes, there are a number of things to consider with this heat generator: choosing the right type of heat pump, finding the optimal installation site, as well as the costs. But besides that, especially with an air-to-water heat pump with an outdoor unit, the noise level is an important factor that should be taken into account. But how loud is a heat pump as a rule? Are there any limit values? And what can you do to reduce the volume of the newly installed or existing heat pump? We will address these and other questions in the following guide.

How loud is a heat pump?

Due to the way a heat pump works, compressors and fans are used, the latter primarily in air-source heat pumps, which generate noise. Noise emission averages between 50 and 65 decibels (for outdoor units). Decibel (A-weighted) or dB(A) is the unit for sound pressure or noise level according to the internationally standardized A frequency weighting curve. The specific noise levels of a Viessmann heat pump can be found in the product documentation or are best obtained from the installer. It should be noted that the values given are guide values. You should also take into account that 50 to 65 decibels are measured when you stand directly next to the heat pump. This value is already below 45 decibels at a distance of three meters.

Comparison of the volume of the heat pump

The perception of volume and noise is very different. To be able to classify how loud 45 decibels actually are, a comparison is useful. The value corresponds roughly to the hum of a refrigerator or the noise level of quiet rain. Normal road traffic in the immediate vicinity generates about 70 dB(A). A conversation is around 60 dB(A). Even whispering can be described as 30 dB(A). The falling of a feather causes slightly more than 0 dB(A) and is thus at the limit of the human hearing threshold.

Factors influencing heat pump volume

The appropriate installation location is crucial when it comes to the noise level of a heat pump. As already mentioned, the decibel value decreases with distance from the unit. The position also plays a decisive role. The noise emission can increase under canopies or between two walls. Such locations should be avoided at best during installation. The output also determines the noise level of a heat pump. Heat pumps in the low output range are significantly quieter. In addition, two very basic aspects also determine heat pump loudness: indoor and outdoor installation and the type of heat pump. There are different specifications to consider for the design - indoor and outdoor unit as well as split design - which you will find listed in the following section. The pure outdoor installation in monobloc design, where all essential processes take place outside in the unit, are somewhat louder compared to the indoor installation or split design. The volume plays a subordinate role for the water-to-water and the brine-to-water heat pumps.

Factors at a glance:

  • Installation location
  • Design / construction
  • Heat pump type

Measures to reduce the noise level

The measures to reduce the noise level of heat pumps are varied, but should always start with professional advice and planning. Our Viessmann partners check the possible location and plan certain measures in advance.

Noise control measures for outdoor and indoor installation

Among other things, it should be noted that heat pumps installed outdoors should maintain a minimum distance of at least three meters from the neighboring property. In the best case, the outdoor unit should not face a bedroom or children's room window. Exhaust fans should also be mounted facing away from other houses, if possible. As mentioned above, the outdoor unit should also not be located under a canopy or even in a niche or corner. There, the volume could be amplified as if by an echo. For indoor units, a sound-absorbing base can help, such as a concrete base with rubber matting. Intake and exhaust vents should not be near a bedroom, even in your own home. It is also a good idea not to install the heat pump in a completely empty room and, if necessary, to include a soundproof door.

Downstream solutions and what you can do yourself

As shown, the installation location and the position to your own as well as to neighboring houses is crucial. However, conditions may have changed over time. Sound-reducing measures for units that have already been erected, such as retrofitting insulation to the compressor or other components, as well as installing a soundproof hood, should be done by your trusted installer. One of the last measures should be the relocation of the heat pump. This should also be done by the expert.

To ensure quiet night operation in particular, storage systems and underfloor heating play a role. Buffer storage tanks and underfloor heating systems store heat in the building. If these are available, the heat pump output can be lowered at night. A low output noticeably reduces the noise level. In addition, a hot water storage tank makes for quieter nights by moving water heating to the early morning hours. Storage tanks and panel heaters can also be retrofitted very easily.

But you yourself can also help reduce noise emissions, for example by planting a hedge or erecting soundproof walls. Special sound insulation panels can be just as useful.

How loud can a heat pump be at all? - Limits and regulations

How loud a heat pump can be depends largely on the time of day and the residential area. At night, the heaters should run quieter than during the day. As far as the type of settlement is concerned, heat pumps may be louder in purely industrial areas. In order to have concrete guideline values and a basis for interpretation, the Technical Instructions for Noise Protection, TA Lärm for short, was published as an administrative regulation by the Federal Immission Control Act (BImSchG). The following overview provides an overview of the values in different areas at daytime and nighttime.

ResidenceLimit value dayLimit value night
Spa area45 dB(A)35 dB(A)
Pure residential area50 dB(A)35 dB(A)
General residential area / small residential area55 dB(A)40 dB(A)
Mixed area60 dB(A)45 dB(A)
Urban area63 dB(A)45 dB(A)
Commercial area65 dB(A)50 dB(A)
Industrial area70 dB(A)70 dB(A)

You can find detailed information, including the advantages in terms of volume and noise of Viessmann heat pumps, in the section "Air-to-water heat pumps: volume and sound".

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