25 cm to 30 cm. The ceiling height of different air conditioners is different, the lowest is about 200 mm, and the highest may reach 600 mm. When installing, don't stick it on the top surface, there will be * * * vibration when sticking it, and you can't stick it on the ceiling below. Leave some backwater slope under the ceiling. Pay attention to the slope of drainage during installation, which can be larger and controlled at about 2 to 3 cm, so that drainage will be smoother and will not be blocked, and the difficulties caused by maintenance will be prevented. For low floors, the fuselage should not be too thick, so as not to feel depressed when installing.