For "220V Cooling Fan", because they can all work within 12 ~ 30V, 12V considering the wind speed is too low, 30V high fever, do not take the big problem 18V, but also to test the lower and upper and lower limits to measure its ability to start ceiling test "220V Cooling Fan" of fever and heat resistance, because the bad environment, high temperature work, if the work can be stable at high voltage, the thermal stability is better. However, the fan long run, over a two to three years will generally bad, we must consider the insurance, especially its power supply in parallel with the relay coil, must be considered a good question after a short "220V Cooling Fan".