Usually in the process of building a kitchen, there are many sizes for the installation of ventilation flues. The first is that there must be an inseparable relationship according to the number of floors of the building. Ventilation flues on higher floors should be larger, and flues on lower floors should be smaller. The cross-sectional dimensions of ventilation flues used in daily life are: 320X240 for floors below 6 floors, 340X300 for floors below 12 floors, 460X400 for floors below 24 floors, and so on.