Air heat pumps are a sustainable alternative to gas or oil heating systems. But how does it work, what costs are involved and what is the experience with it? In this article, you'll learn everything you need to know about air heat pumps.

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What is an air source heat pump?

An air source heat pump is a heating system that absorbs heat from the surrounding air and uses it to heat buildings and produce hot water. It is the most widely used type of heat pump and the most common alternative to traditional heating systems such as oil and gas heaters.

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How does an air heat pump work?

An air heat pump extracts heat from the ambient air and transfers it to a refrigerant, which evaporates even at a low temperature. A compressor increases the pressure of the gaseous refrigerant and heats it to the necessary flow temperature. The resulting heat is then transferred to the heating system via a heat exchanger. The refrigerant then expands and liquefies. The cycle starts from the beginning.

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There are two types of air heat pumps: air to water and air to air heat pumps. They only differentiate in the type of heat distribution.

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air to water heat pump

An air-water heat pump can treat heating and hot water. If it is equipped with a cooling function, it can also function as an air conditioner in summer. It is connected to water-based heat distribution systems and supplies both floor heating systems and low-temperature radiators. This makes it ideal for retrofitting existing buildings.

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air-to-air heat pump

An air-to-air heat pump transfers the generated heat directly to the room air and does not require any water-based heating systems. Instead, it distributes heat in the building via a ventilation system. Since it cannot generate hot water, a separate water heating system is required. It is particularly suitable for well-insulated new buildings with controlled residential ventilation, such as passive houses.

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How much does an air heat pump cost?

An air heat pump costs between 8,000 and 17,000 euros, depending on performance and model. Add Assembly costs of 3,000 to 8,000 euros. The total costs for an air heat pump therefore amount to 11,000 to 25,000 euros.

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Are air heat pumps promoted?

Air heat pumps are supported by subsidies and low-interest loans as part of the Federal Funding for Efficient Buildings (BEG).

• When replacing the heater, you can KfW subsidy 458 that covers up to 70% of eligible costs, with a maximum of 21,000 euros being possible for a single-family home.
• Alternatively, the KfW loan 358/359 available with an effective annual interest rate of 0.01%, which can be used in addition to existing subsidies and allows loans of up to 120,000 euros per residential unit. Householders with an annual income of up to 90,000 euros benefit from particularly low interest rates.

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Is an air heat pump worth it?

An air heat pump is worthwhile because, due to their high efficiency, they only have low operating costs. Particularly when replacing heating systems, the investment is worthwhile due to funding of up to 70%. The acquisition costs are then significantly reduced and the investment pays off more quickly. Especially in well-insulated buildings, an air heat pump is a cost-effective and sustainable alternative to gas heating.

The following example shows that an air heat pump is more worthwhile in the long term than gas heating. Lower operating costs and government funding result in a Savings of 14,500 euros in 20 years.

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What is the experience with air heat pumps?

Numerous test and experience reports show that air heat pumps are an efficient heating solution — both in new buildings and in existing buildings.

In a Test report from BR24 air heat pumps from six different manufacturers were tested in practice. The testers analyze Efficiency, volume, and costs. They point out that the correct sizing of the system is particularly important to avoid efficiency losses and high electricity costs.

Auch Long-term experiences of homeowners confirm the positive results. In a Erdgas Südwest experience report A user who has been operating an air heat pump since 2004 describes that the system is working reliably and that no major maintenance problems have occurred. It highlights that The noise level in everyday life is not annoying is and that heating costs have developed positively in the long term.

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How loud is an air source heat pump?

Depending on the model and operating mode, an air heat pump produces a volume of 30 to 60 dB. In Low-load operation Is it as quiet as a whisper (30—40 dB) while below full load reaches approximately the volume of a conversation or a dishwasher (50-60 dB). Proper installation and sound insulation reduce potential noise emissions.

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Are air heat pumps also efficient in old buildings?

A comprehensive analysis is provided by Fraunhofer ISE heat pump field test, which has been investigating the operation of heat pumps in existing residential buildings since 2019. Die Interim results of 2024 confirm that modern heat pumps also work efficiently in old buildings. Even at low outdoor temperatures, they achieve stable performance values.

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Air heat pump put to the test: Which is the best?

The best heat pumps come from leading manufacturers, which are characterized by high efficiency, durable technology and good customer reviews. The most well-known brands include: Viessmann, Vaillant, Stiebel Eltron, Buderus, Mitsubishi Electric.

According to the Heat pump test by Stiftung Warentest Are they Buderus Logatherm WlW186i-10 AR E And the Weishaupt Biblock WBB 12 Test winner. Both models were characterized by high energy efficiency and good environmental properties and received the Overall score 2.3 (good).

More heat pumps rated “good” Are they LG Electronics Therma V (overall score 2.4) and the Panasonic Aquarea L-Series KIT WC09L3E5 (Overall score 2.5). Die Alpha Innotec Hybrox 8 On the other hand, only the Overall rating “satisfactory” (2.8), as it had the highest power consumption in the test and was less efficient in colder climates.

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What are the advantages and disadvantages of air heat pumps?

Air heat pumps are the cheapest type of heat pump. It is also easy and flexible to install. However, efficiency depends on the outside temperature and their operation produces noise.

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Is an air source heat pump the right choice?

Whether an air heat pump is the right choice depends on individual circumstances. It is particularly worthwhile in well-insulated buildings with a low flow temperature and can save money in the long term through government funding and low operating costs. It is particularly efficient in regions with mild climates or in combination with photovoltaics. For poorly insulated old buildings or very low temperatures, an alternative heat pump or a hybrid solution may be more suitable.

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