The heat pump systems

The various types of heat pump differ in terms of efficiency, energy source and price. Here is what to consider.

Heat from the environment

Either air or water is used for heat absorption and heat dissipation. This results in different types of heat pumps, for example an air-to-air heat pump. The first part of the name stands for the heat absorption, the second for the heat emission. Heat pumps are very economical because they use existing heat. However, the decisive factor for the efficiency of a heat pump is not the actual temperature of the heat source, but only the temperature difference between the absorption medium (air, water, antifreeze) and the heat source. The greater this difference, the more efficiently the heat pump works. Heat can be extracted even when the ‘heat source’ is at minus 10°C. Heat pumps therefore require no fuel and can be operated entirely with renewable energy – cleanly and in an environmentally friendly manner. The house requires no chimney, gas line or oil tank.

The principle of operation

The operating principle of a heat pump is the same as that of a refrigerator – only in reverse. The heat that is extracted from the interior of a refrigerator is supplied to the house in the case of a heat pump. Of course, the process also works in the other direction: a house can also be cooled with the heat pump. The circuit below explains the basic principle of a heat pump.

Vaporisation through heat absorption: Heat from the air, water or ground warms the heat transfer medium via a heat exchanger. The heat transfer medium is a liquid that vaporises even at low temperatures.
Heat concentration through compression: The heat density of the evaporated heat transfer medium is increased by compressing it using a compressor. This raises the temperature. Figuratively speaking, it is a bit like shovelling gravel into a pile: There is now more gravel in a smaller space – in the case of the heat pump, more heat.
Condensation due to heat emission: The heat transfer medium emits its heat to a heat user, e.g. a heating circuit or a heat storage tank. This causes the heat transfer medium to condense and liquefy again.
Expansion through pressure reduction: The now cooled and liquid heat transfer medium is still under pressure. This pressure is reduced by means of a valve. This causes the heat transfer medium to cool further. The cycle can begin again.

Like a refrigerator, but in reverse: the operating principle of heat pumps.

The systems

Each system has different strengths. Here is an initial overview:

description	heat absorption	heat output	efficiency	costs	other
air-air-heat pump	exhaust air	supply air	high	middle
air-water heat pump	outside air	heating circuit	high	middle
groundsource heatpump	earth	heating circuit	very high	rather high	May require authorisation for geothermal drilling
water-water heat pump	groundwater	heating circuit	very high	rather high	requires authorisation

air-air heat pump

A heat exchanger that extracts heat from the outgoing air and transfers it to the incoming air. A ventilation system is required for the house. The process is efficient, but the transferable energy is limited. The ideal application for this type of system is in Minergie-P houses.

air-water heat pump

Air-to-water heat pumps are an ideal replacement for existing heating systems. They do not require extensive conversions and can be put into operation quickly. This type of heat pump uses the heat from the outside air. Accordingly, the outside temperature can play a role (operation down to -20 °C possible).

groundsource heatpump

This type absorbs heat from the earth. To do this, it requires either a geothermal probe (laid at a depth of 100-300 metres) or shallow surface collectors. Due to the construction measures required, brine-water heat pumps are particularly interesting for new buildings. The great strength of the system is that the ambient temperatures are irrelevant for operation.

water-water heat pump

The water-to-water heat pump uses an existing water source to absorb heat. This is usually groundwater (a drilling permit is required). Thanks to the stable temperatures of the groundwater throughout the year, it is an ideal heat source. Newer water-to-water heat pumps can also use waste water or surface water as a heat source.

This is what an air-to-water heat pump can look like.

Prerequisites

A heat pump can be operated in basically any house. In new buildings, water-water heat pumps or brine-water heat pumps are particularly worthwhile, since excavation work has to be done anyway. The necessary preparations for the heat pumps can be realised with little additional effort. For retrofitting, heat pumps that use air as a heat source (air-air heat pumps and air-water heat pumps) are particularly suitable. How well a heat pump pays off depends mainly on the required temperatures and the conditions of the house. Ideally, the house has underfloor heating or otherwise large convectors (radiators). This is because heat pumps do not work with very high temperatures. Whether a heat pump in a house can provide the required heating can be checked with a simple procedure: On a cold winter’s day, the conventional heating system is set to 50°C and the radiators are then switched on. This roughly simulates the situation with a heat pump. If the apartment warms up to a comfortable temperature, there is no reason not to install a heat pump immediately. If the heating output cannot be implemented, the remedy is to increase the radiator surface area, e.g. with more or larger convectors. From a financial point of view, this additional investment usually pays off after a few years. From a comfort point of view, the investment pays off immediately: more pleasant and better heat distribution and less dry air.

The features of heat pumps at a glance

Heat pumps make a lot of sense from both a financial and an ecological point of view. Heating costs and environmental pollution are drastically reduced. The slightly higher initial investment compared to a gas or oil heating system pays off after just a few years. It is important to obtain the electricity from a guaranteed ecological source, preferably from your own roof. Find out how it works here.

Best price-performance ratio over the entire service life
reduction of energy costs
Reducing dependence on fossil fuels
Increase in security of supply and price stability
Energy fully renewable (with solar system)
No CO2 emissions
No odour or other negative impact on air quality
Small footprint

Funding programmes for heat pumps

The federal government’s ‘building programme’ supports the cantonal programmes and sets the framework for them. However, each canton designs its own funding programme individually. Some funding programmes also exist at the municipal level. As a result, there are some major differences for cantons and municipalities. However, the cantons agreed on a minimum funding level in 2015. In the case of a heating replacement (oil/gas), this consists of a basic contribution of 1600 CHF plus an additional 60 CHF/kW. A heat pump with a heating output of 9 kW is thus subsidised with CHF 2140. However, many cantons go well beyond this minimum funding, e.g. the canton of Bern, which provides funding of 10,000 CHF (max. 35% of the actual costs).

Conclusion

Heat pumps make sense in almost every house – especially in combination with a photovoltaic system. This connection is important: if the electricity is not produced renewably, but comes from a coal- or nuclear-fired power plant, the advantages of a heat pump are drastically reduced. Solar systems, on the other hand, produce electricity exclusively sustainably. You can find more information about the sustainability of solar installations here. In fact, a heat pump is significantly more economical in combination with a solar energy system. This is because solar energy systems are very cost-effective at generating energy. Find out more about the cost-effectiveness of solar installations here. Now it is important to get a clearer overview of your situation. This is easy to do with the free SolarReport. You can obtain it using the Solar Calculator, which takes into account your individual situation and a heat pump. The SolarReport is an excellent basis for deciding on how to proceed. Find out more here.

Get your SolarReport now – start the solar calculator.

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