Understanding hybrid heating

Advantages of combining multiple heating systems

Reliable, energy-efficient and fit for the future – a hybrid solution combines all of these advantages. Here we explain how a hybrid heating system functions and which combinations are possible.

Hybrid heating is very versatile

Hybrid solutions are increasingly popular, particularly when modernising the heating system in older buildings but also in new constructions. Their advantage lies in the more environmentally friendly, efficient and flexible production of heat, which is why the state rewards these setups with large subsidies. The options for combinations are diverse and depend on your building.

01. What is a hybrid heating system?

Hybrid heating is not a stand-alone new technology. It refers to the combination of two or more heating systems with different energy carriers that are controlled by a shared control unit. The most common combinations are:

Gas hybrid

Gas hybrid heating

Oil hybrid

Oil hybrid heating

As you can see, hybrid heating solutions generally combine fossil energy carriers (gas, oil) with renewable energies (in the form of a heat pump or a solar heating system). This makes the hybrid solution environmentally friendly and saves on heating costs. On the other hand, the fossil energy carriers ensure a continuous heating output. It is also possible to combine multiple renewable energy options. One example of such a hybrid solution would be the combination of a heat pump and a solar thermal system as a “renewable hybrid heating system”.

Hybrid heating systems with solar thermal technology

A solar thermal system from WOLF produces heat from the incident solar radiation. It transfers the heat to the heating system for heating and for domestic hot water. It is stored in a buffer cylinder to ensure that heat is available even at night and on cloudy days.


When combining solar with fossil fuels like gas or oil, the solar thermal system covers the base load. With this hybrid variant, the gas or oil heating system only switches on when more heat is needed. This is generally only the case in winter. Gas hybrid heating solutions with solar heat are particularly popular.

Hybrid heating systems with heat pumps

A heat pump draws its energy from the ambient heat of the environment. Possible energy sources include the air, ground or groundwater, each of which are utilised by one of the three types of heat pump:

Icon Air-to-water heat pump

Air-to-water heat pump

Icon brine-to-water heat pump

Brine-to-water heat pump

Icon Water-to-water heat pump

Water-to-water heat pump

Air-to-water heat pumps are the easiest and quickest to install. The installer need only set up the device itself without any more extensive measures such as boring wells into the ground. Brine-to-water and water-to-water heat pumps are primarily suited for new builds since excavation work is required for their installation. In general, heat pumps operate most efficiently with a low flow temperature. For this reason, they are best suited for underfloor heating and other forms of panel heating. When combined with a condensing heating system, such as the COB-2 oil system or the CGB-2 gas system, the heat pump covers the base heating load, while the other heating system kicks in during peak loads. Because heat pumps require electricity, it is a good idea to supplement the heating system with a photovoltaic system. This will save money on heating costs over the long term. The energy sources themselves are fundamentally available for free, as is the photovoltaic electricity used in this case to operate the heat pump. The only other expenses would be the cost of oil and gas for the periods of peak demand.

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02. Advantages of a hybrid heating system

Whether you choose a renewable, oil or gas hybrid heating solution, all of these systems offer a range of advantages.

Heat pump CHA Efficiency


Both heat generators complement each other, allowing each to play to its strengths, while also making your heat generation especially dependable. Combining two heat generators yields efficiency and operational reliability.
Save costs


You will receive an attractive subsidy for a hybrid heating system and also save on heating costs, since a portion of the energy is available for free. 

Moreover, by including renewable energies in your heating setup, you are no longer as dependent on the price of fossil energy carriers.
solar thermal

Environmentally responsible

Hybrid heating systems are environmentally friendly and exceptionally efficient. Plus, a hybrid heating solution is fit for the future since it integrates renewable energy carriers. 

03. Hybrid heating systems in existing and new buildings

Hybrid solutions are not just for existing buildings. They can also play out their strengths in new constructions. In particular, combining oil or gas heating with solar thermal or a heat pump can significantly reduce heating costs.
  • Hybrid heating in existing buildings

    Owners of detached houses can benefit in particular from the advantages of a hybrid heating solution when modernising their heating setup since they can continue to use a portion of their existing heating system.


    • In some cases, they can even continue to use their existing gas or oil boiler and simply supplement this with a heat generator based on renewable energy.

    • If your boiler is already more than 15 years old, however, it is advisable to replace it with a condensing boiler that can get the most heat out of the expensive fuel.


    This will cut CO2 emissions by up to 30% and save as much as 35% in heating costs. With the modern WOLF control unit, you can configure your hybrid heating system to emit minimum amounts of CO2 while saving as much as possible on heating costs.


    Gas and oil hybrid heating systems are typical in older buildings for the reasons given above. Nevertheless, a hybrid heating setup consisting of only a heat pump and solar thermal system can be realized in existing buildings as well. In this case, however, the costs of additional insulation and replacing radiators with panel heating (such as underfloor heating) will be higher.

  • Hybrid heating in new buildings

    Hybrid heating is particularly advantageous in newly constructed multi-unit buildings. As the builder, you can satisfy the statutory requirement to use renewable energy for a portion of the heating by installing a heat pump. With an additional condensing boiler, such as a modern gas condensing boiler, you will also enjoy absolutely reliable operation.

    A well-insulated building is essential for combining a heat pump with solar thermal technology. This solution is therefore primarily suited for new buildings.


04. Conclusion: Face the future confidently with hybrid heating

With a hybrid heating system, you make yourself less dependent on the oil or gas price in the long run. Thanks to lucrative subsidies and the energy savings, the additional expense of a hybrid solution can be recouped in just a few years.


Frequently asked questions about hybrid heating

  • Condensing technology extracts heat from the exhaust gas, especially from the water vapour present in this gas. As a result, condensing boilers utilise a particularly high share of the heating energy available in the fuel. If you have an older appliance without condensing technology, a replacement is definitely worthwhile.

    • In dual alternative operation, the heat pump alone provides the heat when temperatures outside are moderate. If the temperature falls below the so-called dual mode point, the hybrid heating system switches off the heat pump and the condensing boiler takes over the heating. This solution is the simplest, but generally the least efficient and least environmentally friendly.
    • In dual parallel operation, the heat pump always runs and the fossil heat generator sometimes runs at the same time.
    • In dual semi-parallel operation, the heat pump and condensing boiler run together at moderate outside temperatures. If the temperature is mild, only the heat pump runs. If it is very cold, only the gas heating is used.
  • With older gas heating systems, conversion to a gas hybrid setup is somewhat more difficult. Newer condensing boilers are often already fitted with a compatible control unit. In this case, it is very easy. In other words, it is simpler if you replace the old gas boiler at the same time and supplement it with renewable energies.

    The subsidies offered for such a new gas hybrid heating system are also more attractive. If you convert to gas hybrid heating within two years of buying the gas condensing boiler, however, you will still receive the BEG subsidy (“renewable ready”).

  • Compared with gas heating, oil emits more CO2. For this reason, the German federal government has decided that oil boilers should no longer be used for heating over the long term. oil heating systems are therefore not eligible for subsidies, even as part of a hybrid system.

  • A buffer cylinder is a central element of a hybrid heating setup. It ensures that all parts of the hybrid system function optimally and independently of each other. It also offers the greatest flexibility when replacing a heating generator or adding a new one.


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