It operates nonstop, nonstop, and at a steady rate of 97% of the time, so producing a continuous flow of air throughout the entire apartment (1 room). Therefore, the real service life that I can tell you is 3.5 to 4 years, then it starts to make such a noise with a crash, I don't even know why compare, but only a person who is absolutely deaf can bear such a sound, so you throw it away and purchase a new one, as I do. In conclusion, the real service life that I can tell you is 3.5 to 4 years. I