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Consumer review group Stiftung Warentest compares air/water heat pumps: The winner is Viessmann’s Vitocal 250-A

The Vitocal 250-A has now emerged from a Stiftung Warentest comparison as the best air/water heat pump. This innovative unit thus underscores Viessmann's technology leadership and high quality standards.

Test winner Vitocal 250-A
  • Top test result in energy efficiency and environmental characteristics
  • One of the quietest heat pumps of its kind
  • Viessmann One Base makes it easy to use

Allendorf (Eder), September 28, 2023 – Efficient, climate-friendly, especially quiet and well-suited for modernization – the Vitocal 250-A air/water heat pump has it all. And it’s the best of its kind: The innovative heat pump came out the clear winner in the recently published test by Stiftung Warentest, garnering an overall rating of “GOOD” (2.1). 

Top result in energy efficiency and environmental characteristics

The Vitocal 250-A also earned the top rating (“GOOD”  or 2.1) in the key assessment criterion “Energy efficiency and environmental characteristics when heating.” It was the only heat pump of all tested devices with annual electricity consumption under 5000 kWh (assessed using a model home with 140 m² living space and an annual heat consumption of 150 kilowatt hours per square meter). Because the heat pump is also operated using the natural refrigerant R290 (propane), the device also contributes to climate protection. R290 (propane) is considered to be one of the most environmentally friendly refrigerants, with an extremely low GWP100 (global warming potential) of 0.02 (according to IPCC AR6).  

Quiet as a whisper in full and partial load operation

An extra bonus of the Vitocal 250-A is the particularly quiet operation of the exterior device. The fan features a low-noise design and employs an intelligent speed control unit that significantly reduces air noise during full and partial load operation. Extensive development work in the Viessmann Acoustic Laboratory, one of the most modern acoustic laboratories in Europe, means that the heat pump’s fans and compressors are almost imperceptibly quiet. This makes the Vitocal 250-A one of the quietest of its kind, at 30 dB(A) in noise-reduced operation at a distance of four meters. It is therefore no problem to install the external units in densely built-up areas or near property lines.

A grade of 1.6 for easy usability

Be it for the installation and commissioning or the controls on the device or through the ViCare app – the easy, uncomplicated operation of the device earned it a grade of 1.6. The patented Hydro AutoControl hydraulic system greatly accelerates the installation of the new heat pumps. It ensures that the devices adapt to almost all available heating systems during the modernization process and eliminates the kind of time-consuming installation work that other heat pumps require. That’s a huge advantage for Viessmann’s specialist partners in the trade sectors.

The Viessmann One Base operating system seamlessly connects the heat pump to digital and physical service offers of the highest quality. This enables convenient operation by users via their smartphones and the ViCare app, as well as straightforward commissioning, comprehensive system monitoring and remote maintenance by specialist companies using the ViGuide service tool. Trade partners not only save a lot of time – their customers also enjoy maximum convenience, highest security and energy efficiency as well as a comprehensive range of services for their systems. In addition, the Viessmann One Base also enables seamless communication with the Vitocharge VX3 electricity storage system and photovoltaic system. These components allow the heat pump to be used for most of the day using affordable self-generated electricity.

Energy Management system provides transparency regarding consumption and costs

In addition, the ViCare App’s integrated energy management assesses all energy flow between the heat pump and any available electricity storage systems or batteries as well as a charging station for electric vehicles. This is shown in a graphic on the smartphone or tablet, making energy consumption and production transparent. Expanded ViCare features allow for further savings and comforts, especially in combination with smart room and floor heating thermostats by Viessmann. 

Existing radiators can continue to be used in existing buildings

The air/water heat pump Vitocal 250-A and the compact device Vitocal 252-A, which features the same technology and an integrated 190 liter DHW cylinder, are specifically designed for the modernization of older gas and oil heating systems. They can easily achieve a flow temperature of 70°C, even at very low outdoor temperatures. This means that customers do not necessarily need to install floor heating and, in existing buildings, can simply continue to use their existing radiators. 

With rated heat output of 2.6 to 13.4 kilowatts, they are particularly suited for use in single- and two-family homes, are eligible for subventions and can be purchased or leased via Viessmann trade partners. Additional output ranges up to 18.5 kilowatts will be available at the beginning of next year, expanding the range of use of the devices. 

Additional information on the test can be found in the ARD media library at the following link (in German):


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The winner of the Stiftung Warentest test was the Viessmann air/water heat pump Vitocal 250-A with an overall rating of “GOOD”.

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The Viessmann Vitocal 250-A was the only one of the tested devices with annual energy consumption below 5000 kWh – this earned it the top mark in the test category “Energy efficiency and environmental characteristics when heating.”

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The ViCare App makes the Vitocal 250-A particularly easy to use, the integrated energy management makes transparent all energy flows between the heat pump and any available electricity storage systems or batteries and charging stations for electric vehicles.

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