Heat pumps: information about operating principles, energy sources and subsidies

Operating principles

A heat pump converts environmental energy into heat for your home. First, the heat energy present in water, the ground, outdoor air or extract air is transferred to a refrigerant via a heat exchanger (evaporator). With the aid of a compressor, the refrigerant boosts this energy to a higher temperature level, making it suitable, via another heat exchanger (condenser), for the heating system or DHW heating.

Depending on the energy source, up to five parts environmental energy can be converted to heating energy for one part of electrical energy used. The environmental energy in the form of a temperature of -20 °C to +35 °C (air) must be brought to a temperature level suitable for heating (DHW). During this process, the water is "pumped" from the low temperature level to the required temperature.

Did you know: the use of renewables is set to overtake fossil fuels! With the right energy management, you can efficiently generate and store energy for your home.

Operating modes

Mono mode
Here, the heat pump is the heat generator in the building. This operating mode is suitable for all low temperature heating systems up to 55 °C flow temperature.

Mono energetic
In this operating mode, the electric heat pump is backed up by an electric booster heater. This is required, particularly with air|water heat pumps, to provide sufficient heating output at lower outside temperatures. During the longest runtimes in a temperature range down to approx. -7 °C, the heat pump functions as the sole heat generator. In terms of investment and efficiency, it can make sense to use the booster heater as backup during the few hours when the temperature falls below this value.

Dual mode – alternative
Down to a fixed outside temperature (e.g. 0 °C), the heat pump delivers all of the heating energy. When the temperature falls below this value, the heat pump switches off and the second heat generator takes over the heating operation.

Dual mode – parallel
Down to a certain outside temperature, the heat pump alone delivers the required heating energy. A second heat generator starts at lower temperatures. When the outside temperature falls below the second limit temperature, the heat pump switches off and the second heat generator takes over the entire heating operation. Unlike in dual mode alternative operation, the heat pump provides a much higher proportion of the total annual output.

Where does a heat pump draw its energy from?

Heat source: air

Air heated by the sun is universally available. Air is at its coldest when the most heating energy is needed, such as in winter. However, heat pumps can still extract enough energy for heating at outdoor air temperatures as low as -20 °C. Air|water heat pumps offer the particular advantage of being easy to install, as no extensive ground work or well drilling is required, as in the case of brine heat pumps, for example.

Heat source: ground

Below a depth of approx. 1.20 m to 1.50 m, the ground remains sufficiently warm in Central Europe to allow economical heat pump operation even on cold winter days. Brine|water heat pumps, therefore, have no output fluctuations even at temperatures below freezing. They absorb the heat from the ground through pipes laid underground, through which environmentally friendly brine circulates. The brine, which cannot freeze, conducts the absorbed heat to the heat pump's evaporator. There are two types of brine|water heat pump, which differ in their installation method: the required pipework can be inserted into boreholes drilled deep into the ground, or laid horizontally. Geothermal probes, which are inserted into vertical boreholes, have the advantage in that they do not take up a lot of space. The horizontally laid geothermal collectors, on the other hand, need about two to three times as much ground surface area as the living area to be heated. If your property is large enough, you can use a brine|water heat pump to take advantage of the almost inexhaustible supply of energy available to you from the ground. These heat pumps are, moreover, virtually maintenance-free.

Heat pump comparison

There are many types of heat pump – each works in a different way and makes use of a different energy source. This comparison provides information about energy recovery methods, installation space requirements and other details relating to each type of heat pump. This will help you choose the right heat pump to meet your requirements.

Savings potential when modernising older buildings

When you opt for environmentally friendly and sustainable energy technology, you contribute to the responsible use of natural resources. There is also a lot of potential for savings when modernising older buildings. Independence from finite resources is increasingly important here as well. After all, independence means freedom. This is exactly what you achieve in energy terms with modern heat pumps. Invest once during your modernisation project to enjoy long term benefits. Your personal energy transition also adds value to your property, with the side-effect of conserving fossil fuels. Take a look at our example of a "Detached house from 1983".

Domestic hot water heat pumps

If you need an affordable solution for your domestic hot water: for DHW heating from renewables, the DHW heat pump offers a quick and convenient solution. DHW heat pumps are affordable to buy and easy to install. They are outstandingly efficient, as the heat is recovered from the ambient air at the installation site.