Indirect secondary ventilation The following example shows the graphic representation of indirect secondary ventilation. Connect the ventilation pipes to the downpipe and to the waste water pipe on the floor. In the component library, expand the Ventilation end point/ventilation valve group with the right mouse button and select the ventilation end point. Place the ventilation end point at the end of the ventilation duct. Note: The layer connection is created automatically during detection. Example of indirect secondary ventilation after detection: