How do turbo expanders work

How do air-to-air heat pumps work?

Classic heat pumps use the thermal energy from air, earth and groundwaterto use Refrigerant and compressor / compressor To gain heating energy. This is then used to warm the room by means of water-bearing heating surfaces. Compared to an air / water heat pump, an air / air heat pump also uses air as a heat source. However, the Heat distribution not via a heating water system, but rather over the air.

Air / air heat pump as part of air heating

The best known is the use of air-to-air heat pumps in connection with a central home ventilation or air heating system. Here it works as an extended part of the Heat recovery: In heating mode, a large part of the thermal energy contained in the extracted air is first transferred to the cold outside air by means of an (enthalpy) heat exchanger. The heat pump unit also uses the residual energy of the exhaust air before it flows outside in order to bring the preheated supply air to the temperature level required for room heating.

The performance and efficiency of such an air heating system can be increased in connection with an air-geothermal heat exchanger: Here, the outside air drawn in, which flows through an air duct laid in the ground, is preheated in winter and slightly cooled in summer.

Advantages and disadvantages of an air-to-air heat pump

The Investment and installation costs of air / air heat pumps, in connection with air heating, are in comparison to separate heating and ventilation systems cheaper. Funding is possible through low-interest loans and repayment grants in the KfW programs "Energy-efficient building and renovation". Alternatively, the subsequent installation of a ventilation system in old buildings is subsidized as part of federal funding for efficient buildings.

The relative is also advantageous less space required. This is especially true for Compact devicesthat integrate all essential functions: ventilation and heating as well as hot water preparation, for which some manufacturers also install a hot water storage tank and an air / water heat pump. As an alternative, a separate hot water heat pump can be used.

However, air heating systems (with air-to-air heat pumps) are primarily suitable for the Use in the passive house and in the KfW Efficiency House 40 (Plus). Because in the home sector, the air volume flows and supply air temperatures can only be increased to a limited extent - in terms of technology, efficiency and comfort. In order to cover the entire room heating load or to increase the heating comfort for the residents, the installation complementary electric heating systemssuch as B. (fan) convectors or surface heating systems, be necessary or recommended - especially in the bathrooms or z. B. also in seldom heated rooms.

In addition, in winter, residents must ensure that the Indoor air over longer phases not too dry is.

Read more about this here.

Zehnder ComfoClime System room climate system solution: the heart of the system is the central ComfoAir Q comfort ventilation unit (with enthalpy exchanger for heat / moisture recovery) in combination with the new ComfoClime Q air / air inverter heat pump. The ComfoHeat hot water heat pump is also used for hot water preparation DHW 300 integrated into the system.

Air-to-air heat pumps are also split air conditioners

Some manufacturers also use the term air / air heat pump for classic split air conditionerswhich, in addition to the cooling function, also have the option of heating a room via the indoor unit. For this purpose, these split air conditioner models use the outside air as a heat source on the one hand and the room air as a heating medium on the other.

One is possible Multi-split mode of operation, where several indoor units are connected to an outdoor unit, which distribute the cool or warm air in several rooms.

Indoor units with specially shaped fins and intelligent sensors, for example, are helpful for more comfortable heating / cooling operation even temperature distribution in the living rooms.

Split air conditioning units are also known as air-to-air heat pumps. With the Perfera series from Daikin, which is available as a wall-mounted or floor-standing unit, the focus is on heating operation. The chest device can z. B. give off radiant heat for 30 minutes and blow out warm air on the underside of the device in the floor area.

In general, these systems can be used for Partial heating, to seasonal use (e.g. during the transition period) or possibly also for Complete heating of a building. The heating specialist should check the desired usage variant in each specific case and discuss it with the homeowner - especially with a view to boundary conditions and aspects such as energetic building standard, technical and comfortable application possibilities / limits, economic efficiency (energy costs), environmental aspects, etc.

You can also read our article "Heating with air-to-air heat pumps" on this subject.