With multiple safeguards, abnormal conditions such as overheating can be prevented. Therefore, the Xiaomi Fan Heater can be used for a long time. However, there will be a circular shadow on the surface of the metal mesh at the air outlet. That is not the malfunction. The circular shadow that appears on the surface of the metal mesh at the air outlet is caused by dust covering the surface of the metal mesh during the use of the heater, which occurs after high-temperature heating. After the heater cools down, disconnect the power connection and wipe the shadow with a dry soft cloth to eliminate it.