Abstract: An exhaust unit for a hanging toilet bowl is described, and includes a house with a back wall and a front wall, two exhaust coupling tubes extending in the house from the front wall to the back wall and having a first end projecting outside the house back wall. The first end of a second exhaust coupling tube can have a diameter that is larger than the diameter of the first end of a first exhaust coupling tube. At its second end, the first exhaust coupling tube can be provided with a sealing ring arranged in a groove-shaped recess of the inner wall. At its second end, the second exhaust coupling tube can provided with a sealing ring arranged in a groove-shaped recess of the inner wall.