Central exhaust air systems can recover and use the heat contained in the exhaust air via a heat exchanger, e.g. to heat domestic water. They are also known as exhaust air heat pumps, as the heat transferred from the room air must be raised to a higher temperature level with the help of a heat pump so that it can be used sensibly.
1 Ventilation unit
2 Heat exchangers
3 Heat pump
4 External air duct (AUL)
5 Exhaust air duct (FOL)
6 Exhaust air duct (ABL)
7 Domestic water
Source: bauwion
