Boiler

The utility model relates to a boiler which is composed of a boiler body, a water jacket, a transverse water pipe, a spiral plate type water jacket, a vertical water pipe, a central water pipe, an upper connecting pipe and a lower connecting pipe of the spiral plate type water jacket, a boiler grate, and a smoke pipe. Because the interior of the boiler body of the utility model is additionally provided with a transverse water pipe with a slope, a central water pipe, a vertical water pipe, a spiral plate type water jacket, and a formed spiral type flue, the heat of the smoke can be fully absorbed, and the purpose of energy saving can be achieved.