In newly built homes, heat pumps have already moved up to number 2 on the list of preferred heating systems. And the upward trend is set to continue. After all, heat pumps are hard to beat when it comes to environmental awareness and energy efficiency. And here's another plus: they operate with low emissions and are very reliable.
With conventional heating systems, heat is generated by burning fossil fuels such as oil or gas. The way a heat pump works is completely different. It operates with electricity and uses heat that is naturally stored in the air, ground and groundwater. A differentiation is made between air source heat pumps, ground source heat pumps that use brine, and ground source heat pumps that use water, depending on which heat source is used.
Heat pumps are operated with a refrigerant that is at an initial temperature of -5 °C to -10 °C. It is warmed by the heat from the ambient heat source, which causes it to evaporate. The now gaseous refrigerant is compressed in the compressor. This brings the temperature up to as much as 70 °C. The heat is extracted in the condenser for DHW and central heating. This causes the refrigerant to cool and become liquid again. The pressure is reduced, which causes the temperature to drop back to -5 °C to -10 °C. The cycle then begins again.
Heat pumps are essentially a new form of technology applied to a tried and trusted principle. They operate exactly like a standard refrigerator – just in reverse.
Air source heat pumps use heat from the air, so installation costs are lower. They are also extremely suitable for modernisation projects. The system even functions at very low temperatures of down to -15 °C.
Ground source heat pumps that use brine extract heat from the ground. The ground is a reliable source of energy, because starting at depths of around 10 metres, the soil temperature is a relatively constant 9 °C to 11 °C all year round. This makes them very efficient, even at very low temperatures during the winter.
Ground source heat pumps that use water take groundwater as their heat source – an ideal thermal storage medium. This is because the air temperature and insolation only affect groundwater by about one degree. The average temperature thus remains constant year round. Ground source heat pumps that use water are the most efficient of all heat pumps.
One important cost to factor in is the electricity required. However, some energy providers offer special, more favourable heat pump tariffs. If you choose a green electricity provider, your heating will be completely CO² neutral. If you own a photovoltaic system, you can generate some of the electricity you need yourself from solar energy.
As of April 2015, the Federal Office for Economic Affairs and Export Control (BAFA) has been paying greater subsidies for renewable heating systems. The BAFA even pays subsidies for later improvements to an already subsidised system.
For an air source heat pump, tapping into the heat source is not complicated at all: air is everywhere, so the heat pump can simply be placed next to the house or in the basement or a storage room. You do not need any special permits beforehand; you simply need to observe the building regulations governing noise reduction. This is rarely a problem, since most heat pumps are designed for extremely low noise operation. On the other hand, air source heat pumps are not as efficient as other types of heat pump.
A few things must also be considered with ground source heat pumps that use brine. Depending on the soil characteristics, tapping into this heat source involves earthwork expenses that may be costly in some cases. For horizontally laid geothermal collectors, you will need sufficient space, and vertically drilled geothermal probes require permits from the water authority.
And if you choose a ground source heat pump that uses water? Then your first step is to get a permit from the water authority to build a suction well and a dry well. Given that the water quality and the volume must meet strict requirements, it is important to drill a sample well first. You can quickly find out which heat pump would be suitable for your home by arranging a meeting with a specialist.