Function of a heat pump

Even though there are different types of heat pumps, they all work according to the same actually quite simple principle. The heat pump extracts heat from its environment and conducts it to where it is needed: Into your living space.

The most important facts about the function of a heat pump


Works like an inverted refrigerator


Draws energy from water, air or earth


Heats in winter and cools in summer


Easy to install and operate

Like an inverted refrigerator

In principle, a heat pump works like a refrigerator. However, while the refrigerator extracts heat from its interior and releases it outside, the heat pump extracts heat from its environment and releases it into the living space. The refrigerant plays an important role in the functioning of the heat pump. In the refrigeration circuit – the heart of the heat pump - this refrigerant circulates, which is liquid or gaseous depending on the temperature and pressure conditions. This refrigerant absorbs the supplied energy from the earth, water or air. In the refrigeration circuit, this temperature is further increased by pressure and finally delivered to the heating system.

Explained simply in 4 steps

1. The environmental heat is transferred to the refrigerant. This heating causes the refrigerant to evaporate. 2. The refrigerant is compressed and heated even more. 3. The heat is extracted from the warm gas and transferred to the heating system. During this cooling process, the refrigerant liquefies again. 4. The pressure of the liquefied refrigerant is reduced, causing the refrigerant to cool down and the cycle starts again (1.).

The most important terms around the heat pump

Heat pumps in comparison


The most popular

The air source heat pump is installed indoors or outdoors. No other heat pump can be installed so quickly and cost-effectively.

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cta wärmepumpen erdwärme visualization
Earth probe

The longest term

The ground source heat pump is installed compactly in the house. In the long term, no other heating system is as cost-effective.

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cta wärmepumpen Grundwasser Visualization

The most efficient

The water heat pump is also installed in the house. It is worthwhile for larger outputs where a lot of energy can be saved.

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Questions about the function of a heat pump

Our references

221010-ROMAN_air-eau_Bramois (1)

Living in and with nature

Eleven buildings with a total of 110 flats. This is "Les Rives de Bramois" in Sion. Remarkably, the buildings only account for 20% of the site area. The remaining 80% are sustainable green spaces and places for non-motorised traffic.

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Oil tanks are out; air source heat pumps are in

Owing to his job at Swisshaus, the owner had already established an interest in heating technology as part of the energy transition. Now, he’s also taken this home with him. The oil heating system gave way to an external air source heat pump from CTA.

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New building

Air source heat pump for an apartment house

The new, quiet, high-performance heat pump from CTA is an ideal fit for the linear architectural style of this new apartment house with view over Lake Thun.

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Renovation with ground-source heat pump

Renewable heating in a heritage-protected building

The Schenini family lives in a sustainably inhabited house. Sustainable, because this timber-framed building has allowed people to live here for generations. It is now also heated sustainably: the old oil-fired heating system has been replaced by a CTA ground-source heat pump.

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Harvesting air as a pair

In this farmhouse, the existing oil-fired heating system was replaced with two interconnected air/water source heat pumps using the natural refrigerant propane. The building owner is now happy to be able to heat the farmhouse using sustainable energy and an environmentally friendly refrigerant.

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12 opinions, one solution

Using a clever redevelopment strategy, the owner of the “Alte Schmitte” development in Lohn-Ammannsegg replaced the power-hungry electric heaters of the 1980s with efficient and economical geothermal heat pumps from CTA. Each flat now has a heat pump that is roughly the size of a wardrobe. For heating and hot water, these use heat from a geothermal probe field common to each building.

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