Air-to-water heat pump

The air-to-water heat pump uses the outdoor air as a heat source to heat the heating water. It is the easiest type of heat pump to install.

How a heat pump works: the refrigerant cycle

Evaporator: the cold refrigerant absorbs heat from the air, ground or water and evaporates.
Compressor: it compresses the vapour, which increases the temperature. Electricity is needed here.
Condenser: the hot vapour releases its heat to the heating water and becomes liquid again.
Expansion valve: the pressure drops, the refrigerant cools down, and the cycle starts all over again.

Schematic. Blue is the cold side, orange the warm side of the cycle.

An air-to-water heat pump uses a fan to draw in outdoor air, extracts heat from it and transfers this to the water in your heating and hot water systems. This also works in sub-zero temperatures, but efficiency decreases the colder it gets.

Advantages

According to klimaaktiv, air is an infinitely available heat source that requires the least technical effort to install. Boreholes or wells are not necessary. According to klimaaktiv, air-source heat pumps are also highly efficient heating systems, and there are no objections to using them.

Disadvantages

Because the outdoor temperature fluctuates significantly over the course of the year, the efficiency is lower than with geothermal energy or groundwater.
The outdoor unit generates noise. The location must be chosen so that neighbours are not disturbed, see sound power level.
In winter, the unit must defrost regularly.
Cooling is only possible when the compressor is running. Geothermal systems, on the other hand, can provide gentle cooling without running the heat pump itself.

Designs

There are monobloc units, where the entire refrigerant circuit is located in the outdoor unit, and split units with an outdoor and indoor unit.

For your house

The decisive factor is the required flow temperature. You can read about whether air or geothermal energy is a better fit in Air or geothermal energy. You can estimate the noise level at the neighbouring property using the noise calculator.

Sources

All terms · Heat pump knowledge