Types of heat pumps

Heat pumps are among the cleanest and most efficient heating technologies. Since they use the existing thermal energy from the environment, they protect the climate and the consumption costs of the system owners. The best-known types of heat pumps include air-water heat pumps, brine-water heat pumps, water-water heat pumps, hot-water heat pumps and large heat pumps. 

Air source heat pumps 

An air-water heat pump extracts heat from the outside or room air and transfers it to a built-in heat exchanger (evaporator). A refrigerant circulates in it and starts to evaporate at a low temperature. Since the temperature obtained during evaporation is too low for the heating system, it is compressed. The compression process and the associated increase in temperature are identical for every heat pump. 

Ground source heat pumps 

There is an enormous amount of energy in the ground, which is almost inexhaustible. With the help of a brine-water heat pump, a fraction of this energy can be used for heating and hot water production. There are two common methods of providing heat to the heat pump: ground loop collectors are laid close to the surface and absorb thermal energy over their large surfaces, which is then passed on to the heat pump. Geothermal probes, on the other hand, are inserted vertically or obliquely into the ground and generate thermal energy from a depth of 40 to 100 metres. Their space requirement is consequently smaller than that of ground loop collectors.

Compared to air-water heat pumps, brine-water heat pumps generally achieve higher efficiencies - irrespective of the method of heat recovery. However, the planning requirements are higher due to the large amount of space required. 

Water-water heat pumps

Groundwater is also an excellent energy store, providing constant temperatures of over ten degrees Celsius throughout the year. In order for a water-water heat pump to operate economically, several factors such as the water composition and the amount of water must be taken into account in advance. A decisive aspect in the planning of such a heat pump is water protection. In some cases, the competent authorities may refuse to approve a water-water heat pump. A corresponding application must therefore be made to the authorities before the purchase.

Hot water heat pumps

A hot-water heat pump is only used to produce hot water. Both recirculated air and exhaust air can be used as heat sources. It is isolated from the actual heating system and can make optimum use of solar power with appropriate components. If the hot-water heat pump uses the circulating air as a heat source, it dehumidifies the room and thus protects it from the risk of mould growth. However, if it is combined with an existing air distribution system, it can even aerate and ventilate the rooms in a controlled manner. An active supply air line is required to prevent negative pressure.

Large heat pumps

Heat pumps are relevant not only for single and multi-family home owners. Businesses and communities also rely on this efficient and clean technology. Highly efficient systems are used which are designed for permanently high requirements and which cover a wide performance spectrum. Similar to most heat pumps in the lower output range, many large heat pumps can also be used for cooling. Detailed information can be found in the section on large heat pumps


Those who use the thermal energy to heat and produce hot water not only save money but also reduce the impact on the climate. For this reason, the government promotes the purchase of such a system with attractive subsidy programmes.