HVAC (the second edition) published in November 2007 defines air conditioning as regulating and controlling the temperature, humidity, cleanliness and air flow rate in a room or space, and providing sufficient fresh air. Air conditioning can realize the comprehensive control of building thermal and humid environment and air quality. The central air conditioner of the all air system has all the functions to deal with the above problems at the same time Refrigeration, heating, central fresh air, PM0.3 filtration, humidification, dehumidification, ultraviolet sterilization, low energy consumption, low noise and other functions are truly central processing systems for human comfortable air environment.