The air flow range is 1000 m3/h~6000 m3/h, applicable to sites such as homes, conference rooms, labs, offices, equipment rooms, restaurants and gyms. The installation is convenient. The machine is installed in the ceiling, without occupying the indoor effective space. More complete functions are implemented, including bidirectional ventilation, air purification, and energy recovery. The sheet metal structure is designed, with thermal insulation cotton stuck inside.