Viessmann heat pump: all info at a glance

Heat pumps are the first choice for those who want to lower their heating bills and generate heat in a more environmentally responsible way. After all, the environment provides heat pump heating with the unlimited, free supply of the energy it needs. This fully-fledged heating system needs very little power for the drive and pump in order to make this energy usable. A heat pump works independently of fossil fuels and actively contributes to reducing CO2 emissions and protecting the climate.

Summary of the benefits of the heat pump

Efficient use of freely available energy from the ground, air, groundwater or the sun
More independence from fossil fuels such as oil or gas
Contribution to the reduction in CO₂ emissions
Combination with a mechanical ventilation unit helps create a complete air conditioning system

Advanced and individual solutions from Viessmann

Viessmann heat pumps offer additional benefits. The new Vitocal outdoor unit, for example, is characterised by particularly quiet operation thanks to its advanced acoustic design. In addition, most Viessmann heat pumps have the active cooling and natural cooling functions. Alongside their classic application as heat generators on cold days, they can also create a pleasant room climate in summer by bringing refreshing cool air into the house. How this function works in detail is explained in the section entitled Natural and active cooling section.

Viessmann's extensive product range offers the right heat pump to suit every demand. As early as the design stage, structural and geological conditions, as well as personal preferences concerning heat demand, can be taken into account. In addition to efficient mono mode operation, heat pumps can be operated with solar systems and together with an existing oil or gas heating system in a multivalent system. This allows individual preferences to be implemented with particular ease.
Different heating systems require different temperatures. Heating with radiators, for example, requires temperatures of up to 70 degrees Celsius. Underfloor heating, on the other hand, manages with a flow temperature of just 35 degrees Celsius. To ensure the most economical operation of a heat pump heating system, the overall heating system is important. Viessmann heat pumps can supply both underfloor heating and radiators with sufficient heat. This makes them suitable for both the modernisation of an older building and for new build projects.

Note on refrigerants used

Heat pumps need refrigerants: Today's heat pumps mostly contain fluorinated greenhouse gases (F-gases). These are either harmful to the climate (so-called HFCs) or pollute the environment via water pollution (so-called HFOs). The sustainable alternative is natural refrigerants (for example propane/R290). In reporting on per- and polyfluorinated chemicals (PFASs), refrigerants in heat pumps have been described as "toxic" - but this only applies to HFOs. Natural KMs including R290 and HFCs are not toxic. Viessmann is converting all heat pumps to natural refrigerants (R290) in perspective. Currently we are still using the HFCs R32, R410A, R407C. The two HFO domestic hot water heat pumps will be replaced by 2024. The HFO large heat pumps will be gradually converted over the next few years.

Germany and the EU are tightening the rules for refrigerants for more climate and environmental protection. Viessmann actively supports an accelerated direct switch to natural refrigerants without a "detour" via HFOs. An ambitious new regulation is not a "brakeman" for heat pump targets (as many from the chemical or airco industry often claim): it creates legal certainty for billions invested in heat pumps and supports a rapid ramp-up.  

We support BEG funding in Germany with incentives for natural refrigerants:  

  • Since 01.01.2023: additional subsidy bonus of 5% for heat pumps with natural refrigerants.  
  • 01.01.2028: in principle, only heat pumps with natural refrigerants will be eligible for support

Renting a heat pump – convenient and simple

Did you know that you can also rent a heat pump? You benefit from no acquisition costs and an express warranty of up to 15  years. Select heat package now at  Viessmann Wärme.

Heating according to the refrigerator principle

The heat pump works according to a simple principle and is amazingly effective. Put simply, it works like a refrigerator –– but in reverse. While a refrigerator directs heat to the outside, heat pumps take energy from the ground, the air or the groundwater and transfer it into the living space via the heating system.

Getting hotter towards the centre: At an initial temperature of between 5 and 18 °C, a flow temperature of up to 72 °C is achieved.

Refrigerant circuit of Viessmann heat pumps briefly explained

The design of the refrigerant circuit is crucial for the efficiency of a heat pump. Viessmann uses the most advanced components for this. They are characterised by quiet operation, low vibrations and an extremely long service life. To generate heat, thermal energy is extracted from the environment and used to evaporate a refrigerant that boils at a low temperature. The electrically driven compressor compresses the gas this creates and raises it to a higher temperature level. A heat exchanger transfers the energy from the heated gas to the heating circuit. The refrigerant, which is still under pressure, condenses again and is expanded in an expansion valve. The temperature drops sharply in the process. The cycle, and with it the heating with heat pump, then start again.

You can learn in detail about how this process works in the section entitled How the heat pump works. You will also find a summary of the power requirements of a heat pump and tips on how to reduce electricity costs.

Viessmann heat pump generations since 1978 till 2022

Generation I

Clockwise from top left to bottom right: Heat pump L08, heat pump L02, heat pump WWK-02, Vitocal 300 (type BW).

Generation II

Clockwise from top left to bottom right: Vitocal 300 (type WW), Vitotres, Vitocal 350, Vitocal 350 with Vitocell 100.

Generation III

Clockwise from top left to bottom right: Vitocal 300-G, Vitocal 200-S, Vitocal 300-A, Vitocal 200-A.

Latest Generation

Vitocal 250-A: The high quality air/water heat pump in monoblock design with a flow temperature of up to 70 °C especially for modernization. Output range: 7.3 to 8.1 kW (for A7/W35). With One Base (E3) control generation. Outdoor unit in Vitographit.

The types of heat pump differ according to the energy source

Heat pumps use environmental energy to heat rooms and water. This requires different sources to be tapped. The best heat source for the heat pump in each individual case depends on local conditions and the heat demand. Viessmann heat pumps have been on the market since the 1970s and use various energy sources:

  • Air
  • Ground
  • Water
  • Waste heat
  • Ice store

Homeowners and modernisers have a wide choice of heat pumps from Viessmann, with models to suit all heat sources and needs. With the right technology from Viessmann, you can keep your heating costs low from day one, and reduce the burden on the environment.

Heat from the air

Air is available everywhere, and it's free of charge. In addition, ambient air always contains heat –– even if it feels chilly outside. The lower, physical temperature limit is -273.15 degrees Celsius. This means that any temperature above this still contains thermal energy that can be used. Even if it might be possible in theory, economical operation with an air source heat pump can only be achieved down to around -20 degrees Celsius. The heat pump can be positioned both indoors and out. For detailed information on how this heat pump works, see: How the air source heat pump works.

[1] Vitocal heat pump
[2] DHW cylinder
[3] Heating water buffer cylinder

Heat from the ground (probe)

An enormous amount of energy lies dormant in the earth, and it's almost inexhaustible. This heat source boasts relatively high and constant temperatures. Starting at a depth of around 10 metres, these temperatures remain relatively high, even throughout the winter. As depth increases, so do temperatures, and with them the amount of thermal energy. With the help of a brine/water heat pump, a fraction of this energy can be used for central heating and DHW.

There are two common methods of providing heat for the heat pump. Geothermal collectors such as surface and trench collectors or energy absorbing mats are laid close to the surface and absorb thermal energy over their large surfaces in order to then transfer it to the heat pump. Geothermal probes, on the other hand, are sunk into the earth vertically or at an angle and extract thermal energy from a depth of 40 to 100 metres. Accordingly, they require less space than geothermal collectors.

When compared to air source heat pumps, brine/water heat pumps generally achieve higher efficiencies, regardless of the method of heat extraction. On the other hand, the planning effort is higher due to the large amount of space required, or the official approval. For more information on this heat source, see the section entitled How the brine/water heat pump works.

[1] Vitocal heat pump
[2] DHW cylinder
[3] Heating water buffer cylinder

Heat from groundwater

Groundwater is also an excellent energy store, providing constant temperatures of over ten degrees Celsius all year round. In order to be able to use the thermal energy, a well system consisting of delivery and return wells is needed. A key aspect when planning this kind of heat pump is water protection. In some circumstances, the responsible authorities may refuse to grant approval for a water/water heat pump. It is important to make a corresponding enquiry with the authority before purchasing.

But even in areas where a well system is permitted, this does not automatically mean economic operation. This is because the composition of the water has a decisive influence on smooth and efficient heat pump operation. If use of a water/water heat pump is not possible, the brine/water heat pump with ice stores or geothermal collectors is a good alternative in practice.

[1] Vitocal heat pump
[2] DHW cylinder
[3] Heating water buffer cylinder

A  DHW heat pump  is only used to provide DHW. Both recirculation air and extract air can be used as heat sources. It is decoupled from the actual heating system and, with the appropriate components, can make optimum use of self-generated solar power. If the DHW heat pump uses the recirculation air as a heat source, it also dehumidifies the room and thus protects it from the risk of mould growth. If, on the other hand, it is coupled to an existing air distribution system, it can even ventilate rooms in a controlled manner. To avoid negative pressure, an active ventilation air pipe is required. Viessmann DHW heat pumps are designed for recirculation or extract air operation and are optionally available with an integrated solar heat exchanger and solar control unit for direct use of solar energy.

Heat from the ground, the air and the sun (ice store system)

The ice store concept combines airborne and geothermal energy, and can also use insolation as a heat source. The ice store system is suitable for all buildings with high heat or cooling demands. This is why it is mainly used in commercial and local authority projects. The ice store is a cistern filled with water that is buried just below the surface of the earth. Inside is a spiral of pipes, which in turn have antifreeze flowing through them. The water in the cistern serves as a heat source, using, among other things, the heat in the earth to regenerate itself again and again. If the ice store is combined with a solar/air absorber on the roof, this extracts heat from the ambient air and solar radiation and feeds it into the storage unit. You can learn more about the process in detail in the section entitled Ice energy store.

Ice store for cooling: In the summer months, the ice energy store can also be used to cool buildings naturally. For this purpose, the water in the ice store is turned to ice at the end of the heating season by extracting energy and interrupting the regeneration process. The resulting ice serves as a reservoir for natural cooling.

[1] Vitocal heat pump
[2] Ice store
[3] Solar/air absorber

Heat pumps are not only of interest to owners of detached houses and apartment buildings. Commercial enterprises, local authorities and industry also rely on this efficient and clean technology. Highly efficient systems are used, designed for permanently high requirements and offering a wide range of outputs. Large Viessmann heat pumps cover output ranges from 50 to 600  kW and can also cope with high flow temperatures of up to 90  degrees Celsius. In addition to the ground, groundwater and extract air can also be used as a source of heat. In industrial applications in particular, waste heat can also serve as an energy supplier. In any case, large Viessmann heat pumps use free energy sources to the fullest extent possible. Large heat pumps are even more effective when used in combination with an ice energy store, thus combining the strengths of different heat sources. Similar to most heat pumps in the smaller output range, many large heat pumps can also be used for cooling purpose. For more detailed information, see the section entitled Large heat pumps.

Retrofitting large heat pumps in a dual mode system

Contrary to popular belief, heat pumps are not only used in new build projects in the industrial, commercial or local authority sectors. System owners can also use them in modernisation projects. This is because a large Viessmann heat pump can be perfectly combined with existing heating systems. So traditional oil or gas heating systems can be supplemented with a heat pump. The heat pump is used to take over the base load of DHW and heating energy. In the event of a peak load, either the gas or oil boiler can then be switched on to cover the demand. This form of heating system in industrial settings not only lowers heating costs effectively, but also reduces CO₂ emissions and is therefore an absolute positive when it comes to climate protection.

A comprehensive preparation and planning phase are important

There is a wide choice of heat pumps for commercial and local authorities uses. Each case comes with individual requirements. To find the right heat pump for the case in question, we recommend a comprehensive preparation and planning phase. One of our competent Viessmann partners will be ready to support you.

Cascade of Viessmann Vitocal 300-G-Pro heat pumps

Advice on a heat pump

Obtaining advice before buying a heat pump is essential. You can choose from a wide range of Viessmann experts and partners.

Before buying or renting a heat pump, there are a few questions that need to be answered. After all, the new energy solution needs to suit you and your home. Below, we have listed a few questions that will need to be clarified in advance.  

  • What type of heat pump would you like to have installed?
  • Should the system be for a single-family home or an apartment building?
  • What is the current consumption for heating energy and domestic hot water in your home?
  • Is the heat pump intended for a new building or for an existing building?
  • What needs to be considered when tapping into the different environmental energy sources?
  • Are permits required for drilling or are there regulations governing the distances to adjacent buildings or noise levels?
  • What potential savings can be achieved when compared to other heating systems?
  • What temperatures can be achieved for heating and domestic hot water and is this sufficient for your own heating patterns?
  • Is a buffer or thermal store unit absolutely necessary and why?
  • How can you actively increase the service life through regular maintenance?
  • What accompanying measures should be taken into account when planning a heat pump?
  • What costs will be incurred for its acquisition and how can these be reduced with a state subsidy?
  • What are the costs for efficient operation of a heat pump?
  • Are there sensible combination options, such as a heat pump with solar thermal?

Working with an expert on site, you can access clear answers to these questions during a heat pump consultation. In addition, there are various Viessmann guides as well as brochures and data sheets on heat pumps offering extensive information on the topics.

Coefficient of performance COP –– what does it mean?

Heating with heat pumps from Viessmann means relying on proven technology and protecting the environment at the same time. That's because all appliances feature carefully matched components and a high COP. COP (coefficient of performance) is a snapshot of the ratio of useful heat generated and drive energy used.

When designing a system, however, it's important to take into account the expected operation over a whole year. To do this, the amount of heat delivered is calculated in relation to the total electrical demand of the heat pump system, taking into account the power for pumps, control units, etc. The result is called the seasonal performance factor or SPF.

In simple terms, COP is an important characteristic value for heat pumps. The higher this coefficient, the more efficiently the heat pump works. You can find out which other factors ensure safe and economical operation in the section entitled Buying a heat pump.

High potential for savings

Heat pumps contribute to a careful approach to the environment. At the same time, they offer the opportunity to reduce costs. The following tables illustrate the savings potential.  The following table illustrates the savings potential.

TechnologyGas savingsCO₂ savings/yearEnergy cost savings/year
Air source heat pump  Vitocal 250-A*100 %35 %€1900
Air source heat pump  Vitocal 250-A + power storage*100 %100 %€4440
Gas condensing boiler + hybrid heat pump  Vitocal 250-SH*86 %34 %€1710

* The values given were determined by simulations assuming standard household profiles for the Potsdam site. Single-family house with 4-person household (existing with gas boiler), 150 square metres of living space and a gas consumption of 2500 cubic metres. Rounded consumption costs using standard values (EID). The energy prices of the Federal Statistical Office were used for the economic efficiency calculation. Investment costs: Viessmann gross list price plus average installation costs nationwide (may vary individually).

Note: Our calculations are theoretical examples based on various assumptions and dependent on certain general conditions. We assume no liability for the correctness and transferability to actual systems. The actual costs and possible savings may differ and must be calculated in each individual case based on the specifics of the respective location and the general conditions there.

Detailed information on the possible savings is provided in our brochure "Modernisation Compass", which is available here as a PDF:

Downloads and links on heat pumps

Heating with airborne and geothermal energy –– making the best possible use of renewables. The brochure below provides detailed information on sustainable and environmentally responsible heat generation using heat pumps from Viessmann. It includes an overview of all current heat pumps and their key technical data, as well as lots of useful information about accessories, service, subsidies and financing options.

For detailed information on Viessmann DHW heat pumps, click on the respective datasheet and the additional product information. There you will find all specifications and features summarised for you.

The brochure below provides information on our large heat pumps in output ranges of up to 600  kW and suitable system solutions for different applications and different heat sources.