The outside air, often referred to as fresh air (AUL), is led to the heat exchanger by suction via a pipe network (often with a geothermal collector) and heated there with the waste heat from the exhaust air (ABL). The exhaust air cooled down in this way leaves the heat exchanger as exhaust air (FOL) and is blown out of the building through an exhaust air pipe. The outside air heated in the heat exchanger is distributed to the rooms as supply air (ZUL) via a pipe network.
Source: bauwion
