During the operation of the HVAC system and HVAC system, the gases released when the water is heated, such as hydrogen and oxygen, will cause many adverse effects, which will damage the system and reduce the thermal effect. If these gases cannot be discharged in time, they will have many adverse consequences. . Such as: corrosion caused by oxidation;the formation of air pockets in the radiator;unsmooth and unbalanced hot water circulation, causing some radiators to be locally unheated;noise when the pipeline is running with air;vortex phenomenon in the circulation pump. Therefore, the exhaust gas in the system must be discharged in time, which shows the important role of using the automatic exhaust valve.