In fact, the effect of air purifier is not ideal. If conditions permit, it is recommended that families install fresh air systems. 1. The working principle of fresh air system is imported from abroad. Most families in Europe and America will install fresh air systems, whose function is to ventilate and keep the indoor air fresh (long-term lack of ventilation will lead to many bacteria breeding and insufficient oxygen concentration, which is harmful to health), but fresh air systems came to China because the air pollution in China is more serious. Therefore, the domestic fresh air system has been improved, and besides the function of ventilation, the function of air purification has been added. The working principle of Haoting fresh air system is as follows: Haoting fresh air system is divided into two parts: the main machine is installed in the living room or balcony, which is responsible for purifying outdoor air and introducing it into the room. At the same time, a breathing Bao 'an is installed on the bedroom window to exhaust the dirty air indoors, and then the fresh air flows from the living room to the bedroom by using the air pressure difference between the living room and the bedroom. So as to keep fresh air indoors all the time. Second, the fresh air system is 1 compared with window ventilation. There is no need to open the window, enjoy fresh air for 24 hours, and ensure sufficient ventilation (indoor air is changed 0.5-0.7 times per hour); 2. Avoid noise, dust, mosquitoes and smog caused by window ventilation to make the room quieter and more comfortable; 3. Continuous ventilation can effectively remove indoor odor and moisture and prevent the growth of bacteria and mold; 4. In winter and summer, the fresh air system with total heat exchanger can save energy to a great extent and create a comfortable indoor environment. 5. The fresh air system filters the outdoor air and inputs it indoors, and at the same time discharges the indoor dirty air. 3. The fresh air system is 1 relative to the air purifier, which solves the problem of indoor carbon dioxide exceeding the standard caused by long-term opening of the air purifier. 2. It solves the indoor problem that people are still in unventilated and continuously polluted due to the low efficiency of the air purifier; 3. Ozone pollution caused by some air purifier purification technologies such as electrostatic technology and negative ion plasma is avoided; 4. Solved the problem of temperature and humidity and the loss of purification effect caused by the need to open the window for ventilation after turning on the purifier for a period of time.