Do you know how heat pumps work?

It is definitely worth thinking about investment into a heat pump. It is an effective and ecological solution that can bring not only comfort into your home but also savings on energy costs. Let´s look closer at what heat pumps are and how they actually work. Technical Director of the company SunnyCold, Ing. Petr Rubeš will give us some advice.

Why are heat pumps becoming more popular?

Heat pumps are considered as alternative energy sources, which allow drawing heat from the surrounding environment and further using it for heating or water heating purposes. They reduce consumption of fossil fuels, they work efficiently, and are often economically more advantageous than other heat sources. Thanks to combination of these properties heat pumps are becoming increasingly common in households.

A properly designed heating system with a heat pump is one of the ways to get comfortable heating, cooling and hot water preparation. Although the initial costs may be higher than with other sources, the heat pump achieves significantly lower energy costs. But surely, everything is worth re-calculating, especially with regard to planned use and financial return.

How does a heat pump work?

Heat pump function is often compared to refrigerators. They work on a similar principle, but in reverse. In case of a heat pump, it is a circular process in a closed circuit. The pump gains heat from surrounding environment (air, earth, water), which is accumulated using pipes and then collected into its evaporator.

In the evaporator, the coolant is then heated by so called low-potential ambient heat. Here the liquid state is changed into gaseous state. Subsequently, the gas is sucked in by the compressor, it compresses it and the low-potential heat is heated to about 80 ° C.

Such heated coolant further gets into capacitor, where the heat is “handed over” to the water used for house heating, or for utility water heating. This way the gaseous coolant changes its state to liquid.

But what happens later with the liquid? Thanks to the expansion valve, the liquid cools rapidly and travels back to the evaporator, where it is subsequently reheated. This whole process repeats, while generally up to 75% of energy in this process is gained from natural resources.

The most common heat pumps types and their main benefits

Many factors have to be taken into account when choosing a specific heat pump, so you should know at least the most common types. The heat pump may use regenerative energy from earth, underground water, air. According to the source, from which the pump draws heat we distinguish these most common types: air-water, earth-water, water-water and air-air.

The principle of a heat pump operation is the same for all types. The difference between individual heat pumps types is therefore in where the device draws energy from and where it leads to.


You do not need to go far enough to get an example, even the air conditioning works basically like the air-air type pump. The external unit draws heat from the air around the house, heats the coolant with it, which heats the household air using the internal unit.

This heat pump type is also the easiest for installation. On the other side, because of direct blowing and increased noise, this air-air type does not need to be most appropriate for all rooms in the apartment. So, if you require a little bit greater comfort, focus on other heat pumps types.


Air-water heat pumps are also equipped with an external unit, which draws water from the ambient air. However, in this case transforms the heat to hot water, which can be used for conventional heating or for water heating. If you are choosing from air-water and air-air pumps, make sure to take where and how the outdoor unit is located into account and whether noise will be a problem. Your neighbours will definitely not thank you for a noisy external unit in a dense urban area.  


In case of earth-water and water-water heat pumps, you will look for an external unit, as in previous types in vain. And in some cases, this is downright desirable. If you have a well and if it is suitable for this purpose, it is worthwhile to think about the water-water heat pump type.

However, heat pumps of the earth-water type are still getting more popular. In this case, holes will be drilled in the (mostly) garden, or surface collectors will be installed under the ground level.

Heat pumps are therefore one of the ways, how we can efficiently use easily available ambient sources with great energy, but low temperature and transform them to heat. The overall efficiency of heat pumps can be illustrated by a simple example. The heat pump is an electricity-powered device and thanks to the principle of how it works (coolant compression and state transformation), it is able to transform 1 kW of electricity into 4 kW of heat. Thus, in comparison to other heat sources, pumps have a tremendous advantage.  

Lightning in an intelligent household