Heat pump in a single-family home: The complete 2025 guide
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Stefano Fonseca ist Ingenieur für Energie und Umwelt mit über sechs Jahren Erfahrung in der technischen Gebäudeausrüstung (TGA). Er kombiniert technisches Fachwissen mit einer Leidenschaft für verständliche Kommunikation. Seit mehr als fünf Jahren schreibt er als freiberuflicher Redakteur über erneuerbare Energien und nachhaltiges Wohnen, insbesondere über Photovoltaik und Wärmepumpen.
Heat pumps promise low heating costs and a climate-friendly heat supply. But is it really worthwhile to use it in a single-family home? Which technology is best and what do you need to pay attention to when planning, installing and operating? In this article, you will find out what you need to know about heat pumps in a single-family home.
What is a heat pump and how does it work?
One heat pump is a heating system that uses environmental heat from air, soil or water and converts it into heating energy for your home. It extracts thermal energy from the environment and raises its temperature to a usable level with the help of an electric compressor. This heat is distributed in the house via radiators or floor heating. The circuit consists of an evaporator, a compressor, a condenser and an expansion valve.
Heat pumps are considered a future-proof solution because they do not require any fossil fuels. They work particularly efficiently in well-insulated single-family homes and can be ideally combined with photovoltaics. As a result of rising CO₂ prices, legal requirements and attractive subsidies, they are becoming increasingly important compared to gas or oil heating systems.
Comparing types of heat pumps for single-family homes
Depending on the conditions of the house and property, various types of heat pumps are possible. Each uses a different heat source and has its own advantages and requirements. The choice of suitable technology depends heavily on insulation standards, space conditions and investment costs.
- Air to water heat pump: Uses outdoor air as a heat source and transfers the energy to a water-based heating system. It is easy to install, cost-effective and is suitable for new buildings as well as well-insulated old buildings. However, at very low outdoor temperatures, their efficiency drops noticeably. A space for the outdoor unit is necessary.
- Air to air heat pump: Heats the air in the room directly via a ventilation system. It is particularly suitable for passive houses and buildings with controlled residential ventilation. The purchase costs are low, radiators are not required. However, it works less efficiently at sub-zero temperatures.
- brine water heat pump: Uses geothermal energy via surface collectors or geothermal probes. It offers very high efficiency and provides constant heating output all year round. This requires earthworks, which involve higher costs and permits. Ideal for new buildings or old buildings with a large garden.
- Water-to-water heat pump: Uses groundwater as an energy source and is one of the most efficient heat pumps. The temperature is stable all year round, which makes operation particularly economical. However, use requires a water permit and a constant groundwater level. Development costs are high.
- Hot water heat pump: This compact heat pump is used exclusively for hot water heating. It uses indoor or outdoor air and is easy to combine with existing heating systems. It is ideal for households with low heat requirements. This does not cover the heating operation itself.
- Hybrid heat pump: Hybrid solutions combine a heat pump with a gas or oil condensing boiler. They are particularly suitable for old buildings with high heating requirements. The system primarily uses the heat pump and switches to the fossil system during peak loads. This increases supply security, but does not completely reduce CO₂ emissions.
The following table shows a direct comparison of the most important characteristics of the types of heat pumps mentioned.
How much does a heat pump cost in a single-family home?
In a single-family home, you can expect costs of between 15,000 and 35,000 euros for a heat pump including installation. Air-water heat pumps are the cheapest and cost only around 15,000 to 25,000 euros. Geothermal and groundwater heat pumps are significantly more expensive due to drilling or earthwork and are usually between 25,000 and 35,000 euros.
The actual costs depend on the type of building, the heating requirement and the chosen technology.
State funding for heat pumps in single-family homes
Heat pumps in single-family homes are financed by the Federal Funding for Efficient Buildings (BEG) financially supported. For the heating exchange, you can apply for a subsidy through the KfW 458 program and in addition a low-interest loan via the 358/359 programs.
The KfW subsidy 458 covers up to 70% of eligible costs. In the case of a single-family home, expenditure of up to 30,000 euros is funded, meaning that a maximum of 21,000 euros in subsidy is possible. Private owners who replace their existing heating system with an environmentally friendly heat pump are eligible.
In addition, you can take advantage of a promotional loan with particularly low interest rates starting at 0.01% effective annual interest rate via loans 358 or 359. The credit line is up to 120,000 euros per residential unit. Householders with an annual income of less than 90,000 euros benefit from particularly favourable conditions.
Requirements for heat pumps in single-family homes
For a heat pump in a single-family home to work efficiently, certain technical and structural requirements must be met. This is the only way you can take full advantage of the investment.
These requirements should be met:
- Good building insulation: A low flow temperature is crucial for efficiency. For this, the house must be well insulated, especially the roof, windows and outer walls.
- Suitable heating system: Heat pumps work best with surface heating systems such as floor or wall heating. Alternatively, low-temperature radiators can be used.
- Enough space: Air-water heat pumps require space for an outdoor unit. Sole or water heat pumps require additional space for earthworks or well drilling.
- Power connection with sufficient power: The heat pump must be reliably supplied with electricity. In some cases, a high-voltage connection or a separate heat pump meter is required.
- Hydraulic balancing: To ensure that heat is evenly distributed throughout the house, hydraulic balancing of the heating system is required by law.
- Permits and soil conditions: Official approvals are required for geothermal or groundwater heat pumps. In addition, the soil conditions must be suitable for probes or wells.
Planning and installing a heat pump: The path to a new heating system
The planning and installation of a heat pump in a single-family home requires several steps, which must be carefully coordinated. This ensures that your new heating system works efficiently and is eligible for funding.
Find a specialist company: You should pay attention to this
Hire a certified specialist company with experience in heat pump technology. Pay attention to references and qualifications, such as an entry in the installer directory. An on-site appointment is essential so that the company can assess the structural conditions and recommend the appropriate solution.
Submit funding applications before commissioning
Funding must be applied for before you award the installation contract. You should therefore submit the grant application to KfW in good time. Only then will you actually receive the funding.
Heat load calculation and sizing
A specialist company uses the building envelope to calculate the heat load of the house. On this basis, the appropriate heat pump is selected. A system that is too large or too small works inefficiently and causes unnecessary costs.
Approvals and regulatory requirements
Geothermal or groundwater heat pumps require permits from water or environmental authorities. Contact your municipality early on to find out about the requirements.
Installation process and duration
Depending on the type of heat pump, the installation takes between a few days and several weeks. Air-water heat pumps are the quickest to install. In the case of geothermal probe or well drilling, the construction period is extended due to complex development work. After installation, commissioning and instruction are carried out.
Optimization and maintenance: How to get the most out of it
Efficient operation and regular maintenance ensure the long-term performance of your heat pump. With the right measures, you can get the most out of your investment and avoid expensive failures.
- Optimum settings for maximum efficiency: Set the flow temperature Set as low as possible, values below 35 °C are ideal. Use time programs and a weather-controlled controller and adapt the operation to your everyday life and the weather. A well-coordinated heating curve saves electricity and improves the annual performance factor.
- Maintenance and care of the heat pump: Heat pumps are considered low-maintenance, but you should use the Maintain the plant annually. This includes monitoring the refrigeration circuit, electronics, filters and pressure.
- Common issues and solutions: Typical faults include error messages due to air in the heating system, dirty filters, or sensor problems. Let a specialist company clarify the causes. Many problems can be avoided through regular maintenance and correct operation.
- Lifetime and warranty: Heat pumps achieve a Lifespan of up to 25 years. Depending on the manufacturer, warranty periods vary between 5 and 10 years. When concluding a contract, pay attention to clear conditions for warranty extensions and good customer service.
Combining a heat pump with photovoltaic
The combination of heat pump and photovoltaic reduces your electricity costs and increases your self-consumption rate. Solar power supplies the heat pump directly with energy, making you more independent of the electricity price. At the same time, the carbon footprint of your heating system is improved, as the electricity comes from renewable sources. The solution is particularly efficient with an additional energy storage device, which further increases self-consumption and can also supply the heat pump at night.
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