Heat pump technology

Heat pumps - affordable and efficient heating with environmental energy Contact us

The heat pump is not only an efficient and sustainable heating system, but also an environmentally friendly alternative to fossil energy. Therefore - and this is yet another argument in favour of the heat pump - you can claim subsidies for switching to a heat pump. The heat pump uses energy from air, soil or groundwater and converts it into heating energy. In the following, we will answer the most important questions:

"How exactly does a heat pump work?". "What are the advantages of using a heat pump heating system?". "How much do the installation and operation cost?". "Is there anything else that needs to be taken into consideration?"

We have compiled all the information relating to heat pumps and have put it together for you in a way that is easy to understand.

There are many advantages to heat pumps


Environmentally friendly thanks to the use of energy obtained from the air, soil or water.


The heat pump uses naturally renewable energy from the air, so that you can save money on your fuel bills. Furthermore there is the possibility to apply for subsidies to further reduce costs.


Rising prices for fossil energy hardly take an effect on operating costs.With heat pumps you will be independent from rising prices.


Offers optimal comfort for heating, cooling, hot water and can be ideally combined with photovoltaic systems.

How does a heat pump work

The principle

The basic operating principle of the heat pump is quickly explained: it uses the heat from the air, soil, groundwater and transforms it into heating energy for you to use inside your home. All it requires is electric power. An average heat pump needs about 1 kilowatt hour of electricity to generate 4 kilowatt hours of heating energy - which means that you only pay for one kilowatt hour and get three for free. But the heat pump can do more than just heat: in summer it can also cool down your house or apartment.

See for yourself how the heat pump works with the video on left side.

Heating with a heat pump

When heating, the heat pump operates in the same way as a refrigerator: while the refrigerator extracts heat from the inside and dissipates it to the outside, the heat pump extracts thermal energy from the environment, converts it into heating energy and transfers it to the interior of the building. It does this by absorbing the heat from the environment into a pipe system through which a refrigerant flow that is colder than the outside temperature. The heat from the environment is used to vaporise the refrigerant. This steam is compressed in the so-called compressor of the heat pump. This further increases the temperature until the heat of the steam is eventually transferred to the heating circuit of the building.

Cooling with a heat pump

A heat pump can also function as an air conditioner and be used to cool the house or apartment. This can be done in two different ways, depending on the type of heat pump:

Cooling with a floor heating system:

Ideally, a heat pump works with a panel heating system, i.e. underfloor or wall heating - as it is already present in most new buildings. Rooms can be cooled down via this method by about 3°C and kept at a pleasant temperature. This is usually enough to keep your rooms at a pleasant temperature.

Cooling with a fan coil unit:

In heating systems with radiators, you can cool with fan coils, for example under the roof or in the bedroom. In this way, even lower room temperatures can be achieved - comparable to an air conditioning system. They can be combined both with underfloor heating and radiators.

Hot water produced by a heat pump

A heat pump heating system is used in combination with a hot water cylinder. Vaillant offers separate storages to provide the highest degree of comfort for hot water. We also offer complete solutions in which the hot water cylinder is already integrated into the heat pump system. The solutions offer sufficient hot water comfort.

The three energy sources of the heat pump

The three energy sources of the heat pump

Using energy from the air by means of a heat pump is the most cost-effective of all three options. No official approval is required and deep drilling and excavation work is not necessary. Even when the outside temperature drops as low as -25°C, the heat pump can still produce heat for the heating. Here, the following rule applies: the higher the outside temperature, the more efficiently the heat pump works.

Energy from the ground

The upper layer of the earth is warmed up by continuous solar radiation, resulting in temperatures of around 10°C 10 to 15 metres below the earth's surface including during the winter. Using ground sensors or surface collectors, the heat pump produces heat from the ground to heat up the building. This kind of heat pump involves drilling a hole in the ground or installing a pipeline system roughly twice as large as the living space.

Energy from groundwater

With a constant temperature of around 10°C, groundwater is also a viable source of energy. To use groundwater as an energy source for the heat pump, you need two groundwater wells on your property. It is important that a suitable water source can be accessed for the installation to be completed successfully. Rivers, streams, and lakes are also potential sources. All options require authorisation.

Heat pump costs

If you are considering purchasing a heat pump, you will probably ask yourself this important question: what are the costs involved? The main costs are likely to be the acquisition and installation costs. Next come the operating costs, i.e. the cost of electricity to run the system. As for all heating systems, you also have to factor in an amount for maintenance costs.

In terms of acquisition and development, the air-source heat pump is usually the most affordable option - in this case you will have to invest approx. EUR 10,000 to 12,000. For ground-source heat pumps, you should expect to pay EUR 18,000 to 25,000 due to the necessary excavation work. For the purchase and installation of a water-source heat pump, you also have to spend about EUR 25,000, because you have to build an elaborate well system and that is correspondingly expensive.

Our tip: In new buildings, a geothermal heat pump is most likely "worthwhile", since it has to be built / dug. Suitable for this are our flexoTHERM exclusive and flexoCOMPACT exclusive.

The electricity costs depend on the age and size of the house, number of people living in the household, power rates, geographical location and much more. An important tip: Many utilities offer very favourable rates for the operation of heat pumps.

If you want an exact cost calculation for your heat pump, it is best to contact your installation company, who can go through the individual items with you step by step.

Planning of a new heat pump

First of all, and most importantly: Always seek advice from a qualified company once you have decided to install a heat pump. You should first check with a specialist about which type of heat pump solution is possible or advisable for you. Depending on which energy source you choose, you will have to be aware of unique characteristics.

Modernising with a heat pump

You can plan the installation of a heat pump heating system in new buildings from the very start, but modernising your heating system with a heat pump is also highly recommended for old buildings. Vaillant offers solutions that enable heat pumps to work with underfloor heating as well as radiators. This is because underfloor heating is a panel heating system, which means that due to the larger radiator surface, you need a lower flow temperature when the system is in operation. As a result, the heat pump has to work less and is therefore more efficient.

Replacing oil heating systems is particularly worthwhile, because there is no longer any smell of oil, you gain an entire boiler room and you save money on operating costs.

Overall, modernisation involving a heat pump entails extensive work for you, especially if you have decided on a ground-source or a water-source heat pump. However, you shouldn't forget that you will have significantly lower operating costs from now on and are no longer dependent on fossil energy. In addition, by using a heat pump heating system, you are heating in an environmentally friendly manner and conserving natural resources.

Hybrid heat pump systems and system extensions

In multi-family houses, hybrid heating systems help to satisfy the high heating demand. In single-family homes, hybrid systems are usually used during renovation to expand existing and still functioning heating systems. If there is a high demand for hot water in a detached house, the system can be set up so that the gas provides hot water and the heat pump does the heating.

This is how a hybrid heat pump system works

A hybrid heat pump is a so-called bivalent system, which means that not just one, but two heat sources are utilised to provide heating. Usually the heat pump is combined with a gas heating system, but bivalent operation is also possible with an oil heating system. The heating system regulates which source is used automatically. When the difference between outside temperature and heating temperature is rather slight, the heat pump is able to heat efficiently. If the temperature difference increases, the gas or oil heating system takes over once a certain threshold is reached. Combining a heat pump with a gas or oil heating system makes a lot of sense, especially with an air-source heat pump.

A hybrid heating system consisting of oil or gas combined with a ground-source heat pump or a water-source heat pump is possible, but not practical. The reason is that the relatively constant temperature of the soil and groundwater means that there are no major fluctuations in electricity consumption.

Combination of heat pump and photovoltaic system

Heat pumps can be combined very effectively with a photovoltaic system. The photovoltaic system generates the electricity that the heat pump consumes when in operation. This has two advantages for you: On the one hand, you heat in a sustainable and environmentally friendly way, and on the other hand, you make yourself a little less dependent on energy providers.

More possible heat pump combinations

Alternatively, you can use a bivalent system consisting of a heat pump and solar thermal energy. Unlike the photovoltaic system, this converts solar energy into heat instead of electricity.

Convenient operation is made possible by combining the heat pump with a control unit. From here, you can conveniently select the flow and setback temperature as well as many other settings in order to achieve the heating output that is right for you.

With a ventilation system, you not only ensure healthy air, but you also reduce your heating costs simultaneously. Your Vaillant technician will inform you in person about the possible combinations of your new heating system with a ventilation system.

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