The ingenious way an air-water heat pump works is easy to explain. It uses air as a heat source. Even at very low temperatures down to minus 20 degrees celsius, it can extract sufficient heat from the outside air. But it even knows how to help itself at lower temperatures. It can switch on a heating element in the buffer tank and thus reliably heats your rooms even on those rare days when it is freezing cold in our latitudes.

This seemingly paradoxical process is made possible by special refrigerants that evaporate at low temperatures. The boiling point of the natural refrigerant R290 (propane) is as low as minus 45 degrees celsius and it is also extremely climate-friendly.

In the first step of the refrigeration cycle, a powerful fan draws in the ambient air and directs it to a heat exchanger, the so-called evaporator. The liquid refrigerant circulates here and steadily increases in temperature through contact with the warmer outside air until it finally evaporates.

Once the refrigerant has changed from a liquid to a vapor, it flows on to a compressor. This increases the pressure of the vapor by compressing it, which also raises its temperature.

The refrigerant vapor is brought to the required temperature and then passes to the condenser, another heat exchanger. Here, the hot refrigerant vapor transfers its temperature to the heating water in the heating circuit or the fresh water in the domestic hot water tank. The refrigerant vapor cools down again, condenses and becomes liquid again.

Now your air-water heat pump has “pumped up” the temperature of the air and you can use the energy gained to heat your home and prepare hot water. Before the heat pump's refrigeration cycle starts again, the liquid refrigerant still has to pass through the expansion valve. The pressure and temperature then return to the initial level.

Air-water heat pumps are suitable for heating new buildings as well as for modernizing an existing heating system. They can be installed inside and outside the house.

Basically, the air-water heat pump is available as a monobloc or split device. In the split design, the cooling circuit is partly inside and partly outside the building. The moving and noise-generating parts such as the fan, evaporator and compressor are housed in the outdoor unit. A refrigerant line leads from the outdoor unit to the indoor unit with condenser, circulation pump and control technology.

With the monobloc, the complete cooling circuit is located in a single unit. If the monobloc air-water heat pump is installed outside, it is connected to the indoor unit with a water pipe. Only the warm heating water is then distributed in the heating system via the indoor unit. Indoor units for alpha innotec air-water heat pumps are available either as a wall-mounted controller with circulation pump, as a compact hydraulic module or as a hydraulic tower with in-line buffer cylinder and hot water cylinder - the latter being the perfect complement to our most modern and climate-friendly Hybrox heat pump family.

A space-saving outdoor installation is the preferred solution, especially for modernization. In a new build, you can also plan the location of your air-water heat pump indoors from the outset. Our tip if space is tight both in the garden and in the house: Our Paros air-water heat pump for indoor installation only requires a footprint of 0.3 square meters and can even be installed in the attic thanks to the clever air routing.

Heating with environmental heat is already climate-friendly per se, as only a fraction of the energy is used in the form of electricity. Many energy suppliers offer special heat pump tariffs that are cheaper than conventional electricity tariffs and also come from renewable sources.

Your air-water heat pump works even more economically and climate-friendly if you produce the electricity to run the compressor with your own photovoltaic system.

Conclusion: By combining a highly efficient air-water heat pump with photovoltaics and green electricity, you can optimize the ecological balance of your heating system. This not only protects your wallet, but also the environment.

Although the main task of an air-water heat pump is to heat and prepare hot water, you can also use modern appliances for cooling, as their cooling circuit can be switched at the touch of a button. The heat pump then draws the heat energy from your home and discharges it to the outside. Reversible operation ensures a pleasant indoor climate all year round – in both the cool and warm months.

Like almost every technical system, an air-water heat pump generates unavoidable sounds during operation. However, a modern air-water heat pump from alpha innotec is very quiet thanks to a combination of sound and vibration optimization. Measured directly at the sound source, the noise is in the range of a normal conversation. At a distance of three meters, the sound level of our Hybrox 5 is reduced to around 45 dB(A) – comparable to the gentle humming of a refrigerator.

To avoid complaints, you should always make sure to maintain sufficient distance from neighboring properties and your own bedroom when installing the unit outdoors. For indoor installations, for example in the basement or garage, it is advisable to decouple the sound and install special vibration dampers under the heat pump. This prevents the transmission of noise as unpleasant structure-borne sound to walls, ceilings and pipes.

As an air-water heat pump, this technology has both advantages and disadvantages. Here is an overview:

1. Environmentally friendly: Air-water heat pumps use renewable heat sources such as air to generate heat, resulting in a lower environmental impact.
   
   
2. Energy efficiency: They can generate heat efficiently and are more energy-efficient than conventional heating systems.
   
   
3. Lower operating costs: As they use the ambient air as a heat source, operating costs are lower compared to other heating systems.
   
   
4. Versatility: Air-water heat pumps can be used for heating, hot water and cooling.
   
   
5. Costs compared to geothermal heat pumps: Compared to geothermal collectors or geothermal probes, as required for brine-water heat pumps, air-water systems do not require costly earthworks. This significantly reduces the investment costs.

1. Depending on the outside temperature: The efficiency of air-water heat pumps depends heavily on the outside temperature. The higher the difference between the temperature at the heat source and the flow temperature of the heating system, the more the pressure must be increased – the colder the outside temperature, the more power the heat pump needs.
   
   
2. Noise: Some models can make sounds that can be perceived as disturbing. This can be a problem in residential areas. Seek advice from a specialist partner company and choose a sound and vibration-optimized appliance.
   
   
3. Required space: Air-water heat pumps require space for the installation of outdoor units.
   
   
4. Costs compared to fossil fuel heating systems: The purchase costs for an air-water heat pump can be higher than for conventional heating systems. However, especially in combination with photovoltaics, you can amortize these costs in just a few years thanks to the high level of state subsidies and the savings in operating costs.

Every heat pump works more efficiently than an oil or gas heating system. How economically a heating system operated with an air-water heat pump works depends on many individual factors, such as:

• Building insulation and heat demand in your home
• Self-generated electricity via photovoltaics or external power supply
• Average outdoor temperatures in winter
• Acquisition and operating costs compared to alternative systems
• State subsidies

Be sure to seek advice from trained specialist partner companies. After all, the efficiency and performance of any heat pump stands and falls with the design and correct setting of the system.

However, one thing is certain: heat pumps almost always pay off, even in older buildings. In 2023, WWF Germany showed in a sample calculation that even with the minimum subsidy of 30 percent over 15 years, the heat pump is the cheaper option - and that in a single-family home with energy efficiency class F. If you have photovoltaics on your roof, the additional costs are amortized even faster, as the electricity you produce and use yourself is significantly cheaper than tariff electricity.