Heat pump noise level – limits, comparisons & audio sample

“Many people underestimate how quiet modern heat pumps really are today. In normal operation, they often produce less than 45 decibels—which is about the same as a quiet refrigerator.”

Marion Kirchner, Master Craftswoman in Plumbing and Heating Installation; Head of Sales for alpha innotec Bavaria

The noise level of a heat pump is usually between 35 and 55 dB(A), which is roughly equivalent to the noise level of a quiet conversation. The noise level is determined not only by the heat pump device and how it works, but also by how and where it is installed.

The volume is measured using the parameters of sound power and sound pressure. Sound power indicates how much noise the heat pump itself generates, while sound pressure describes how loud the noise is perceived at a specific point (e.g., the neighboring property). Only sound pressure is relevant for compliance with legal requirements.

All manufacturers specify the sound power level in accordance with DIN EN 12102–1 for day and night operation in their product data. However, the decisive factor is always the noise emissions that reach the neighbors. In construction, the so-called assessment level Lr is used as a measure for this. It is calculated according to a standardized procedure and should always be lower than the applicable limit values.

Calculating sound: The sound calculator of the German Heat Pump Association (Bundesverband Wärmepumpe e.V.).

THE VOLUME OF A HEAT PUMP COMPARED TO EVERYDAY NOISES

SOUND EXAMPLES: HOW LOUD ARE HEAT PUMPS FROM DIFFERENT DISTANCES?

Which heat pump is the quietest?

As a general rule, air-to-water heat pumps are usually louder than geothermal heat pumps or domestic hot water heat pumps. This is because they use a fan to draw in ambient air. Geothermal heat pumps and domestic hot water heat pumps, on the other hand, use groundwater – both without generating any noise.

There are also differences within the device types: modern inverter devices, high-quality housing materials, and a low-vibration design noticeably reduce the noise level.

NOISE LEVEL COMPARISON OF DIFFERENT TYPES OF HEAT PUMPS

Tip: Devices with inverter technology, which regulate their output continuously, are particularly quiet. The refrigerant R290 also enables more efficient and quieter systems with high performance.

To avoid conflicts with neighbors or authorities when heating with a heat pump, legal guidelines for noise emissions must be observed. These are specified in the Technical Instructions on Noise Protection (TA Lärm) and apply at the so-called immission location, i.e., in front of an open window of a living room or bedroom on the neighboring property.

Noise levels according to location 6 a.m. to 10 p.m. / 10 p.m. to 6 a.m.

• Industrial areas 70dB(A) / 70dB(A)
• Commercial areas 65 dB(A) / 50 dB(A)
• Urban areas 63 dB(A) / 45 dB(A)
• Town centers, villages, and mixed-use areas 60 dB(A) / 45 dB(A)
• Residential areas and small settlements 55 dB(A) / 40 dB(A)
• Purely residential areas 50 dB(A) / 35 dB(A)
• Spa areas, hospitals, nursing homes 45 dB(A) / 35 dB(A)

Tip: Specialist partners such as the professionals at alpha innotec can calculate whether and where your device meets all requirements as early as the planning phase.

The noise level of heat pumps depends not only on the device itself, but also on a number of other factors:

• Type of heat pump
  Air-to-water heat pumps are the loudest due to their design, as they use a fan. Brine or water-to-water systems are usually almost silent.

• Quality and insulation of the device
  High-quality devices with vibration-damping construction, sound-optimized housings, and inverter technology operate much more quietly.

• Fan and compressor
  Depending on the speed, fan quality, and bearings, audible differences can occur.

• Installation location & structural environment
  Hard surfaces (e.g., concrete walls, paving stone floors) reflect sound. Corners, courtyards, or walls at a short distance also amplify noise, so outdoor installation is usually louder.

• Wall reflections & floor conditions
  Sound can “accumulate” on walls or be amplified by hard floors. A sound-absorbing surface reduces the noise level.

If you live in a residential area or install them in a confined space, you should pay attention to sound insulation and quiet technology from the outset. Modern heat pumps can now be designed in such a way that they are hardly noticeable.

DESIGN AND TECHNOLOGY

The operating noise of a heat pump depends heavily on its design and technical features. Air source heat pumps, which are among the noisier types of heat pumps, are particularly worth considering carefully when choosing a device. High-quality models with insulated housings, quiet fans, and vibration-free bearings generate significantly lower sound pressure levels.

The refrigerant used also plays a role: heat pumps with propane (R290) offer high efficiency at moderate noise levels. Anyone modernizing the heating system in an old building should therefore pay attention not only to the flow temperature, but also to the noise level in partial load operation, because quiet operation is especially valuable at night to avoid conflicts with neighbors.

INSTALLATION LOCATION INDOORS & OUTDOORS

When installing a heat pump outdoors, the minimum distance to the property boundary is particularly important. In residential areas, a minimum distance of three meters should be maintained, depending on the device and its output, in order to keep the sound pressure levels on neighboring properties below the permissible values.

In addition, your heat pump should be installed as far away as possible from rooms requiring protection and as freely as possible. Sound-reflective walls, floors, and corners near your heat pump can reflect sound and cause the noise level to be higher than calculated.

When operating a heat pump indoors, it is also important to plan for soundproofed rooms and vibration-free foundations. If you have enough space, you can choose an installation location that prevents the operating noise of the heat pump from spreading to bedrooms or adjacent living areas. In short: even simple measures can reduce the noise level.

FURTHER NOISE PROTECTION MEASURES

• Soundproofing hoods or enclosures available specifically for outdoor units
• Vibration-isolating foundations reduce structure-borne noise transmission
• Use greenery or privacy screens as natural sound barriers
• Flexible rubber buffers and mounts to reduce vibrations

Acoustically optimized and properly designed heat pumps are whisper-quiet even at a distance of around one meter.

The noise level of your heat pump during operation depends on several factors. The most important ones are the measured values for the sound power level, the installation location and situation, the tonality, the assessment level, and the applicable immission guidelines.

For more detailed information, we recommend the Sound Guide (as of 2019) published by the German Heat Pump Association (Bundesverband Wärmepumpe e.V.).