Abstract: The constant temperature performance of gas water heater is the focus of the user's attention, gas water heater manufacturers put forward a variety of solutions around the research of constant temperature. But can’t fundamentally solve the problem of long waiting time for hot water, and the problem that the outlet water temperature is sometimes cold and sometimes very hot, can’t solve the problem of the second time you turn on the faucet and will not flow out of cold water. In view of the above problems, this paper proposes a research method to change the design of pipelines and software control of gas water heaters. Firstly, the method adds a water server to the main line and the bypass line of the heat exchanger that automatically adjusts the water according to the required heat during the combustion process. Secondly, the mixture ratio of cold and hot water is accurately adjusted by software. Finally, software control scheme is designed reasonably to control the air-fuel ratio of the combustion process within the setting range. By the above methods, the temperature stability time of the effluent is not more than 8s when the gas water heater is opened, achieve the effect of the hot water temperature changing in±1℃.

Key words: Constant water temperature, Water server