Quiet Page

Our quietest ever heat pump

Why is being quiet important?

In most EU countries, noise protection guidelines apply to public and private areas, so heat pumps sited in indoor and outdoor areas need to comply with this legislation. In Germany, for example, this is the TA-Lärm, while in Switzerland, it is the Noise Protection Ordinance (NPO). Such guidelines specify how high the noise pollution may be.

Key guidelines

Keep a distance

A distinction is usually made between the type of area (e.g. purely residential or industrial), as well as between day and night. Since the noise of a heat pump decreases the further away you are from the receiver, a certain distance is required between the unit and the property in order to comply with noise protection guidelines.

Make it quiet

If the heat pump is already very quiet due to its design, only a short distance needs to be maintained. This is of particular interest in new build and comparatively small properties. As a rule, the distance required between the heat pump and any neighbouring properties is calculated on a project-by-project basis, plus the planned installation site is checked accordingly.

Sound calculations

Sound calculation for Germany

Sound calculations for Switzerland

Sound calculations for Austria

Sound calculation for Denmark

Sound calculations for Netherlands

Quiet

The level of sound emitted from a heat pump is often described in different ways, which can it make it confusing to compare different models. There are two main units to consider, sound power level and sound pressure level.

Sound power vs. sound pressure

Sound power level is measured at the point of emission, i.e. the heat pump, and is affected by the design of the heat pump and the working conditions of the heat pump. The sound power level is not related to the distance from the heat pump as it is a total figure for the sound emitted. Sound pressure level is the measurement taken at the point the sound is received, i.e. 1 metre, 3 metres, or 5 metres from the heat pump. This level reduces the further you are away from the heat pump but can be affected by obstacles that can either increase or decrease the level. So, heat pumps such as the AEROTOP® SX, which have a low sound power level need less distance to achieve a low sound pressure level - offering far more flexibility in where the unit is located outside a property.

How have we made the AEROTOP® SX so quiet?

To heat a single-family house with an air-to-water heat pump with 10 kW heating capacity, up to 4,000m³ of air per hour must flow through the evaporator via the fan. In addition, a compressor is required in the refrigeration circuit compresses the evaporated refrigerant to deliver a usable temperature level. All of this creates noise, so we've included the following features to ensure the AEROTOP® SX runs as quietly as possible:

Insulation

The AEROTOP® SX has housing panels lined with high-end insulation. In addition, both the refrigeration circuit and the hydraulic parts are packed separately in a sound absorption box. This keeps any sound emissions from the compressor to a minimum.

Intake grille

A specially designed intake grille reduces air turbulence (created from the evaporator) before it meets the rotating fan blades. This ensures the air flows through the fan smoothly, lowering sound power and producing a more pleasant sound.

Air ducting

A flow-optimised fan embedded in a specially designed housing ensures the lowest possible flow noise. The airflow is guided and optimised in terms of efficiency, ensuring the same performance at lower fan speed.

Fan

A defined gap between the impeller blades and the casing ensures efficient airflow. This ensures speeds can be reduced with the same power in optimal coordination. This not only reduces noise, but also increases efficiency.

Louvres in front of grille

A fan is surrounded by components that influence the intensity of sound emitted. In the case of open/visible fans, this intensity is highest where the air is discharged. As a result, the AEROTOP® SX features specially designed louvres that reduce the sound intensity, as well as hide the fan behind a modern, contemporary cover.

Damping

The compressor of the AEROTOP® SX has a triple bearing. Therefore, the compressor does not transmit vibrations to the housing, which would otherwise lead to structure-borne noise.

Aspects to consider when positioning outdoors

Sound

The heat pump should be positioned so that it does not affect your neighbours or surrounding properties. The distance required depends on the mounting conditions, the type of area, the sound power of the heat pump itself and local standards. As a result, this must be calculated individually in the design phase.

Free field placement

Anything >3m away from a wall is deemed "free field placement". A general surcharge of 3dB(A) is also applied to the sound power of the heat pump in the open air.

Installation at the house wall

Everything closer than 3m to the house wall is considered to be an "installation at the house wall". Compared to the free field (>3m), the sound level at the house wall increases by a further 3dB(A), i.e. +6dB(A), on the sound power of the heat pump.

Installation in a niche

Niches increase the reflection and, in turn, the sound level. Compared to a house wall, the sound level in a niche increases another 3dB(A) , i.e. +9dB(A), on the sound power of the heat pump.