A gas water heater is a water heater that uses gas as the main energy material and transfers the high temperature heat generated by the combustion of gas to the cold water flowing through the heat exchanger to achieve the purpose of preparing hot water. Gas-fired water heaters are the mainstream water heaters that once occupied the water heater market. Its advantages are that it can be used immediately without waiting, and it has a small footprint, which can save a lot of space for comrades living in the sky. In terms of safety, the gas water heater realizes the separation of heat production and heat supply. It is bathed in the bathroom and installed in the kitchen to avoid the danger of electric leakage during the bathing process.