The doors of the paint mist wall were opened during spraying. The paint mist is collected by means of a paper Andreae filter and a paint stop filter. A fan in the heating appliance extracts the filtered air through the red channel. The filtered air is fed into the heating appliance through a heat exchanger and then blows out through the green exhaust duct.

A second fan in the heating appliance draws fresh air from outside the building. This air is preheated by the heat exchanger which is heated by the extracted filtered air. This air is then passed along a burner or second heat exchanger. The heated air is then blown into the Combi hall and ensures that the correct paint processing temperature prevails in the Combi hall.

Both air flows in the heating appliance are separated from each other. During drying, to save energy, the extracted air from the Combi hall can be partially recirculated (80-85%).