Viessmann once again wins the “Stiftung Warentest” – Vitocal 250-A air/water heat pump continues to impress in 2025

• Viessmann once again wins the “Stiftung Warentest” – Vitocal 250-A air/water heat pump continues to impress in 2025
• Rated 1.0 for the most user-friendly operation
• Very high efficiency thanks to innovative refrigeration circuit design
• Extremely quiet operation

Allendorf (Eder), September 25, 2025 – Following its great success in 2023, a heat pump from Viessmann Climate Solutions has once again been named test winner in the current 10/2025 edition of “Stiftung Warentest”. The Vitocal 250-A air/water heat pump with a rated heat output of 10 kW (type AWO-E AC 251.A10) prevailed over four models from other manufacturers in the test in comparison and was awarded with the quality rating “GOOD (2.0)”. This renewed top ranking underscores Viessmann Climate Solutions' innovative strength in the field of sustainable heating solutions. Viessmann Climate Solutions is part of Carrier Global Corporation (NYSE: CARR), global leader in intelligent climate and energy solutions.

Best score of 1.0 for user-friendly operation 

The Vitocal 250-A impressed in the test with its user-friendly operation – both directly on the device with the 7-inch color touch display, as well as via the intuitive control with the ViCare app. The Vitocal 250-A was the only device in the test group that achieved the top score of 1.0 in the “handling” category. As a result, a complex system with a heat pump, photovoltaics, battery storage and wallbox can be operated easily and conveniently by every system operator. 

Vitocal 250-A impresses with high efficiency and low power consumption in real-world operation

With its high flow temperatures of up to 70 degrees, the heat pump is particularly suitable for modernizing existing buildings. The Vitocal 250-A achieves its high efficiency thanks to its innovative refrigeration circuit design, impressing in real-world operation with low power consumption. “Stiftung Warentest” calculations show that a typical old building with an annual heating energy requirement of 21,000 kilowatt hours consumes only around 6,000 kilowatt hours of electricity per year. Assuming an electricity price of around 20 cents per kilowatt hour, the annual costs, including a second electricity meter, amount to approximately 1,500 euros. In comparison, a gas boiler incurs additional annual costs of 700 to 1,000 euros, depending on the gas price and combustion technology. 

In addition, Viessmann uses the climate-friendly refrigerant propane (R290) in the Vitocal 250-A, offering a future-proof solution for the heating transition in the building sector.

Extremely quiet operation 

Another major advantage of the Vitocal 250-A is its exceptionally quiet operation. The specially sound-optimized fan and intelligent speed control significantly reduce noise levels in both full- and partial-load operation. Thanks to extensive development work in one of Europe's most advanced sound laboratories, the heat pump's fan and compressor are barely audible. With only 35 dB(A) in noise-reduced operation at a distance of five meters and positioned close to a wall, the Vitocal 250-A is one of the quietest devices of its kind. This allows the outdoor unit to be operated without any problems, even in densely built-up areas or close to property boundaries.

Perfectly connected 

Thanks to the unified One Base platform, the heat pump connects seamlessly with digital services. End users can easily control the system via smartphone using the ViCare app, while installers can use the ViGuide service tool for convenient commissioning, comprehensive system monitoring and remote maintenance. This not only saves specialist partners time, but also offers customers maximum convenience, safety, and energy efficiency. In addition, One Base enables seamless communication with other components such as the Vitocharge VX3 electricity storage unit, the photovoltaic system, the ventilation system and the ViCare thermostats. This connectivity allows the heat pump to be operated with cost-effective, self-generated electricity for large parts of the day.

Future-proof and energy-efficient using energy management

Conserving resources and saving costs through energy-efficient, optimized operation of all electrical and thermal-electrical energy systems in the building – this is the strength of energy management, which can be made available to system operators via the ViCare app. 

In addition to controlling the components, energy management combines online-connected devices such as Vitocal heat pumps, the Vitocharge VX3 electricity storage unit, the charging station (charging station for electric vehicles), and thermal hot water storage tanks and consumers into a complete system. This provides the user with functional system management for optimal operation. In this way, many system components in the building can be controlled in a resource-saving and energy-efficient manner.

Patented hydraulics reduce installation costs 

The Vitocal 250-A is equipped with patented Hydro AutoControl hydraulics to significantly speed up installation. This system adapts to almost any existing heating system during modernization, eliminating time-consuming work that is often necessary with other heat pump models. This is a major advantage for installers and reduces costs for system operators.

About Viessmann Climate Solutions

Founded in 1917 as a heating technology manufacturer, today Viessmann Climate Solutions is a leading global provider of sustainable climate (heating, cooling, water and air quality) and renewable energy solutions. The integrated Viessmann Climate Solutions portfolio seamlessly connects products and systems via digital platforms and services, creating an individualized feel-good climate for users. Viessmann Climate Solutions is part of Carrier Global Corporation, global leader in intelligent climate and energy solutions. For more information, visit www.viessmann-climatesolutions.com