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Vitocal 250-A and 252-A: The alternative to gas and oil in existing buildings

Air/water heat pumps Vitocal 250-A and Vitocal 252-A specifically developed for modernization projects | Not necessary to redesign the heating system or floor heating | Huge time savings during installation

The future for this kind of heat generation in existing buildings begins with the innovative Viessmann Vitocal 250-A and Vitocal 252-A heat pumps. Flow temperatures up to 70°C make operation with existing radiators possible.

Allendorf (Eder), Dec 15, 2022  –  Heating systems in existing buildings will have to run on something other than oil or natural gas in the near future. Why? Recent geopolitical events have made the accelerated adoption of renewable energy an inevitability. Policymakers want heat pumps to be key drivers of the energy transition in the building sector. Viessmann developed the innovative Vitocal 250-A and Vitocal 252-A heat pumps specifically for modernizing older gas or oil heating systems. The family business thus taken another huge step forward in line with its mission statement: “We create living spaces for generations to come.”

Existing radiators can continue to be used

The monobloc-design air/water heat pumps can easily achieve flow temperatures as high as 70 °C even when outside temperatures are very low. That means most radiators already installed in the house can continue to be used. There is no need to redesign the heating system or go through the considerable trouble of installing a floor heating system.

The Vitocal 250-A is designed as a particularly space-saving wall-mounted boiler, while the Vitocal 252-A is a floorstanding compact unit with an integral 190-liter DHW cylinder. Both models are available with outputs of 10 and 13 kilowatts (for A7/W35). With a COP (coefficient of performance) of over 5.3 (for A7/W35), they generate more than five times the usable energy from one kilowatt-hour of electricity and the heat from the outside air. The Vitocal 250-A and Vitocal 252-A can optionally be used to cool buildings on hot summer days, too.

Hydro AutoControl considerably speeds up installation

The patented Hydro AutoControl hydraulic system greatly accelerates the installation of the new heat pumps. It ensures that the devices will 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. For example, the system already comes with an integrated and connected heating water buffer cylinder for providing defrosting energy. A flow rate sensor is also integrated and works with the bypass valve to maintain optimum circulation rates. Hydro AutoControl also means the equipment’s footprint is up to 60% lower than that of conventional heat pump systems.

Climate protection with green refrigerant

The green refrigerant used, R290 (propane), is considered to be highly environmentally friendly, with an extremely low GWP100 (global warming potential) of 0.02 (according to IPCC AR6). Since the external unit in the new monobloc heat pumps contains the complete cooling circuit, the refrigerant always remains outside the home. All external units are also delivered completely filled, which reduces installation time and avoids the need to present proof of competence for refrigerants.

Quiet as a whisper in full and partial load operation

Are you operating air/water heat pumps in densely built-up townhouse complexes? Advanced Acoustic Design+ has made the Vitocal 250-A and the Vitocal 252-A some of the quietest units in their class. 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. As a result, these innovative units achieve extremely low noise pressure levels of 35 dB(A) in noise-reduced mode and at a distance of four meters in free-standing installation. It is therefore no problem to install the external units in densely built-up areas or near property lines.

The iF Gold Design Award-winning external units feature a clear, timeless appearance in Diamond Edge design. The Vitographit color scheme underscores the high quality of the weatherproof devices. The external units of the Vitocal heat pumps thus set a new standard in design and harmonize with almost any house facade.

Viessmann One Base for seamless digital service

The Vitocal 250-A and Vitocal 252-A can also be expanded to include a  Vitoair FS  home ventilation system and a Vitovolt PV system with a  Vitocharge VX3  electricity storage system. That means the equipment can run on self-generated solar electricity for much of the day. Viessmann One Base ensures that all system components work together seamlessly with digital services such as the  ViCare  app for controlling the units and the  ViGuide  (formerly Vitoguide) service tool. This makes commissioning, maintaining, servicing and monitoring energy systems much easier and faster. Trade partners not only save a lot of time – their customers also enjoy maximum convenience and energy efficiency as well as the safety of their systems.

Homeowners can also keep track of energy generation and consumption in their homes with the integrated Viessmann Energy Management tool and the free ViCare app. Above all, though, it enables the particularly energy-efficient, resource-conserving and cost-reducing operation of the system.

Service link enables faster responses to malfunctions

Does the system not have access to Wi-Fi? Vitocal 250-A and Vitocal 252-A heat pumps are always connected to the Viessmann service team through cellular technology at no cost to you. Potential malfunctions are reported to your specialist partners in real time and can often be fixed remotely. That eliminates needless on-premise service calls and thus saves time and money.

State subsidies of up to 35 percent

The Vitocal 250-A and Vitocal 252-A heat pumps are highly efficient and generate heat in a particularly climate-friendly manner. The German government offers attractive support for their use in modernization projects. Replacing an old oil or gas heating system with one of these units is rewarded with a grant covering up to 35 percent of the cost of its acquisition and installation as well as the automatic flow balancing. To help customers, the Viessmann FörderProfi (Subsidy Pro supports specialist partners and modernizers from the application stage all the way to the payout of the subsidy.  

Benefits for trade partners

  • Installation and design as easy as a wall-mounted gas boiler
  • Significantly faster installation of the internal unit
  • Around 50% fewer components to install than conventional units
  • Patented Hydro AutoControl hydraulic system
  • No need to maintain minimum flow rate, circulation volume or water temperature during commissioning
  • Service link without Wi-Fi enables faster responses to malfunctions
  • High flow temperatures of 70°C (at outdoor temperatures as low as -15°C)
  • A single operating & service app for all heat generators (from gas condensing boiler to heat pump)
  • Can be split up for easy transport in confined spaces (Vitocal 252-A)

Benefits for users

  • Ideal for modernization with flow temperatures up to 70 °C
  • High efficiency for lower operating costs
  • Protects the climate and environment (Climate Protect+++)
  • Reliable operation and superior efficiency (OptiPerform)
  • Faster responses to malfunctions guaranteed (service link)
  • Integrated energy management system for transparent tracking of energy consumption and costs
  • Active cooling in the summertime

Technical specifications

  • Output: 2.6 to 13.4 kW (for A7/W35)
  • COP value (coefficient of performance): > 5.3 (for A7/W35)
  • Maximum flow temperature: 70°C (down to -10°C)
  • Noise emissions: 35 dB(A) (noise pressure level of the external unit at a distance of 4 m in free-standing installation in noise-reduced mode)

External unit:

  • Dimensions (length [depth] x width x height): 600 x 1144 x 1382 mm
  • Weight: 215 to 221 kg

Vitocal 250-A:

  • Dimensions (length [depth] x width x height): 360 x 450/600 x 920 mm
  • Weight: 48 kg or 55 kg

Vitocal 252-A:

  • Dimensions (length [depth] x width x height): 597 x 600 x 1900 mm
  • Weight: 170 kg or 172 kg
  • Capacity: 190 l


The Vitocal 250-A and Vitocal 252-A modernization heat pumps are already available on the market.

Further information

Information on the topic can also be found on the pages  Alternativen zur Ölheizung  and  Alternativen zur Gasheizung  as well as in the article  Propan-Wärmepumpen.  


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Image 1

The future for this kind of heat generation in existing buildings begins with the innovative Viessmann Vitocal 250-A and Vitocal 252-A heat pumps. Flow temperatures up to 70°C make operation with existing radiators possible.

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Vitocal 250-A is a highly compact wall-mounted heat pump that is almost as easy to install as a conventional wall-mounted gas boiler thanks to the patented Hydro AutoControl hydraulic system.

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Image 3

The compact Vitocal 252-A heat pump features an integrated 190 liter DHW cylinder.