Two fans from an air-to-water heat pump outside a house.
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Building and buying

Heat pumps: functioning, types and costs

Thomas Bott

Heat pump heating systems are becoming increasingly popular in Switzerland. According to the Federal Statistical Office, around 18 percent of buildings in Switzerland were already equipped with this type of heating system in 2017. The figure is rising because in new buildings in particular, heat pumps are used more and more often. No wonder, because they offer numerous advantages. Yet people still tend to have reservations about heat pumps, especially due to the high purchase price. You can find out here what types of heat pumps are available and whether the investment is worthwhile.

In this article

Heat pumps: the basic functioning

In principle, a heat pump heating system consists of three closed circuits. The first circuit is the heat source system. It takes heat from the environment, i.e. from the air, soil or water. This heat then enters the second circuit: the actual heat pump. It is absorbed by an evaporator filled with a special refrigerant. As the name suggests, evaporation occurs in it. This is caused by the sensitivity of the refrigerant, which reacts to the heat supplied. The steam, which is already warm, rises and enters a compressor. This compresses it, releasing heat.

The compressed hot steam enters the condenser. The next circuit is already connected: the heat distribution and storage system. The water contained in it absorbs the heat, and the gas cools down. It condenses at the same time, i.e. turns back into liquid, and flows back to the evaporator via a valve. As the liquid is under pressure, this valve is designed to reduce the pressure. Meanwhile, the third circuit distributes the heat generated throughout the house.

Illustration of possible energy sources for a heat pump. These are: air, ground water and soil. When heat is obtained from the soil, there are two extraction methods, using an earth probe or earth collectors.

As shown here, the energy in the system can come from different sources. The heat pump produces usable hot water and heat for heating.

Types: various different heat pumps are available

There are four widely used types of heat pump that are very similar in terms of their basic functioning. The source of the energy is what makes the difference.

Brine-water heat pumps

Here, the energy comes from the ground, which is why brine-water heat pumps are also called geothermal heat pumps. The pipes of the heat source system wind through the surrounding soil. To protect against frost, the pipes must be placed at least 1.5 meters below ground. In order to provide sufficient heat for a house, the heat source system must cover twice the living area. This means that a lot of underground space is required. Earth probes are an alternative. They take up considerably less space, but require holes at depths of up to 300 meters. This requires a mandatory permit from the relevant canton. Brine-water heat pumps are considered to be very efficient.

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Water-to-water heat pumps

A water-to-water heat pump uses ground water to generate heat. This requires two wells: one to pump the groundwater and one to return it to the ground. Authorization is needed to drill the holes to make the wells. In addition, local regulations regarding water protection must be observed. A water-to-water heat pump is the most efficient out of all the different systems. However, it is possible that the municipality or canton may refuse to allow the system to be put into operation if it has concerns as to whether water protection can be guaranteed.

Air-to-water heat pumps

An air-to-water heat pump does not require any liquid in the heat source system. A fan guides the ambient air directly past the evaporator. This fan can be installed in various locations on the property. Not much space is required, and no authorization is necessary. This system is also considered to be very efficient.

Air-to-air heat pumps

An air-to-air heat pump is a special case. The heating system does not need a refrigerant circuit or a water circuit. Instead, the system draws in fresh ambient air and heats it via a plate heat exchanger using the energy from the used ambient air. However, this principle is only suitable for very well-insulated buildings such as passive houses or houses built according to the Minergie-P standard.

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Requirements: it all depends on the environment

Almost all houses are suitable for the installation of a heat pump, except for an air-to-air heat pump. Whether or not a heat pump can actually be used is determined by the environment and the regulations in force in the municipality and the canton. A large plot of land is necessary for a brine-water heat pump. The ground should also be as flat as possible and not contain any rocks. When using an earth probe, it is important to be able to drill to a depth of 40 to 300 meters. It is therefore absolutely essential to carry out a ground check in advance.

With a water-to-water heat pump, sufficient ground water is necessary. Here too, holes are drilled, so there should be no obstructing materials in the ground. Wells can be dug in various locations, however. Using an air-to-water heat pump is only a problem if the temperature in winter is less than minus 20 degrees Celsius. Below this temperature, the system no longer supplies sufficient heat for the refrigerant in the heat pump.

View of an alpine panorama and Lake Brienz from the small village of Iseltwald.

The use of a brine-to-water heat pump is usually easier in more rural areas because there is more chance of being able to meet the higher space requirements.

Installation: the following points must be taken into account when fitting a heat pump

The ideal place for a heat pump is in the basement of the house. If there is no basement, you will need a separate room with good sound insulation. Otherwise the systems will be audible during operation, and you may be disturbed by the noise. You also need a normal heating circuit with radiators for the heated water to run through. This type of circuit is already in place in most existing buildings.

Costs: investment, operation and maintenance

The investment costs for a heat pump heating system vary greatly. They depend on the type of heat pump, the living area to be heated and the heating system already in place. Roughly speaking, you should plan to spend between 30,000 and 60,000 francs. This makes heat pump heating much more expensive to purchase than oil or gas heating, for example.

However, the operating costs make all the difference because a heat pump is particularly cost effective. There are virtually no costs incurred for the energy sources because you won’t need to purchase air, water and earth from a supplier. Having said this, you will still need electricity to make the heat pump work. For an average four-person household, the provider Hoval reckons with around 500 francs per year. In addition, there is an annual maintenance charge of around 200 francs. The high investment required for heat pump heating is therefore offset by the low operating costs. This makes these systems very economical and sustainable. Depending on consumption and the type of heat pump, this type of heating system can pay for itself after only five to ten years. However, in some cases it may take considerably longer.

Subsidies: cantons provide funding for heat pumps

In general, a heat pump is eligible for subsidies because it is a more environmentally friendly and sustainable way of generating energy. Many cantons reward the fact that heat pump heating is so ecological in relation to systems that run on fossil fuels. Das Gebäudeprogramm (federal and cantonal funding program) forms the basis for this. It is up to the individual cantons to decide how much they will contribute.

If you are interested in a heat pump heating system, you should contact your canton to find out about the possible subsidies available. Also ask if a bonus is offered for the heat distribution system.

Heat pumps: advantages and disadvantages at a glance

  • Advantages
  • Disadvantages
  • Choose from four different types of heat pumps to suit your circumstances.
  • Not every type of heat pump heating is suitable for every property.
  • Fuel costs are not high but can fluctuate.
  • In some cases, there can be extensive bureaucratic hurdles in obtaining the necessary permits (especially for earth probes and wells).
  • Mostly compatible with an existing heating circuit when changing the heating system.
  • Very high investment costs compared to other heating systems.
  • High efficiency of heat pump heating in relation to many other heating systems.
  • Subsidy amounts vary greatly from canton to canton.
  • Environmentally friendly heat and hot water production.
  • -
  • Subsidies may be offered by the relevant canton, possibly even with a bonus.
  • -
  • No reliance on fossil fuels and external energy suppliers.
  • -

Conclusion: clean heating with the power of nature

Don’t be put off by the high purchase costs because heat pump heating is an environmentally friendly alternative to many other heating systems, as well as being economical in the long term. Instead of relying on fossil fuels, you heat with a sustainable heat source. Heat pumps are very efficient and can also be combined with other energy sources. To reduce the environmental impact even more, you could generate the necessary electricity yourself using a photovoltaic system, for example.

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