The ventilation fan uses the motor to drive the blades to rotate to realize the exchange of indoor and outdoor air. However, the exhaust fan can only complete partial exhaust, and cannot allow a large amount of outdoor air to enter the room, so it cannot achieve real air circulation. And because the exhaust fan operates in one direction, it can only exhaust indoor air. In addition, the length of the pipe will weaken the exhaust force during operation, so it is only suitable for installation in the living room with good air circulation, not in the kitchen and bathroom. The huge noise generated during its operation makes it impossible to install in the bedroom, otherwise it will affect people's rest.

This will be more obvious in autumn and winter. The cold wind outside. It's so comfortable to come home with a warm current. In this case, who wants to open the window for ventilation. It is very difficult to raise the temperature above 20 degrees in the home. Within half an hour of opening the window, the indoor temperature may drop to more than 10 degrees. If it's windy outside, you don't open the windows for days. But when people live in such an environment for a long time, the body will appear symptoms such as dizziness and nausea. Chest tightness etc. These are all symptoms of hypoxia.