In order to comply with noise protection limits, the majority of heat pumps must therefore be operated at partial load overnight (night setback). However, electricity consumption increases when the heat pump runs at reduced output and more of the required heat has to be generated electrically. The fan is mainly responsible for the noise emissions of the heat pump. For functional reasons, it can only be fitted with sound insulation at great expense.

Air-to-water heat pumps

With the FPowlet, Ziehl-Abegg has a new axial fan in its range that has been specially developed to meet the requirements of air-to-water heat pumps for residential and commercial buildings. The specific installation conditions in heat pumps, such as disturbances in the supply air flow or short nozzle geometries, require measures to solve the problems identified. In addition to improving the air flow rate, the development focused in particular on noise reduction through the fan blade.

Inspired by bionic developments, a "blade" with a special blade shape was created. This enables quieter operation with the same volume flow compared to conventional fans. This means that a higher air and therefore thermal output can be achieved when the sound immission threshold is reached. In other words: with the same air flow and the same thermal output, the fan is quieter than fans currently in use - by up to 4.5 dB(A) depending on the device and installation situation. This means that more heat output is available during night-time operation, which also improves the annual coefficient of performance (COP) of the heat pump.

Coordinated drive

For maximum system efficiency, all components of a system must fit together perfectly. The fan is therefore driven by an EC motor, which is matched to the fan blade with demand-controlled speed and modern communication interfaces. In addition to quieter operation, this also improves energy efficiency. In addition to the measurable volume, the tonality emitted by the fan is also an important factor. A tonal noise is dominated by one frequency, which can be perceived as particularly annoying. During the development of the FPowlet, particular emphasis was placed on reducing such disturbing noises as much as possible.

The optimum interaction between heat pump and fan is crucial. It therefore makes sense to include the fan in the development stage of new appliances. At Ziehl-Abegg, appliances are measured and analyzed on the air side. The installation of the fan is thus optimally adapted to the heat pump according to the problem. Experience has shown that you should not just rely on calculations. A test often reveals the true spectrum of noise behavior. The new FPowlet axial fans are available in various sizes (450-630) for heat pumps. Other fan series are available for more powerful systems.