LIQUID HEATER

PROBLEM TO BE SOLVED: To provide a liquid heater capable of avoiding the noise in the heater by preventing the partial bumping of liquid in a liquid bath, and at the same time easily cleaning the heat exchange section with the liquid. SOLUTION: The liquid heater comprises a water bath 1 for retaining water, a water supply means 2 for supplying water into the water bath 1, a combustion chamber 3 where a gas burner 10 is arranged, exhaust piping 4 that is arranged in the water bath 1, at the same time is connected to the combustion chamber 3 for circulating air that is heated by the gas burner 10 and for heating water in the water bath 1, and a water supply pipe 5 for guiding the hot water in the water bath 1 to the outside of the water bath 1. In the liquid heater, the exhaust piping 4 is made of a cylindrical member that is arranged nearly horizontally in the water bath 1, a fin 6 extended in the longitudinal direction is formed on the inner-periphery surface, and at the same time water in the water bath 1 is heated on the outer-periphery surface.