The invention discloses a direct-heating hot water boiler which is composed of a boiler body, a fume 
pipe, a 
combustor, filler, a 
chimney and the like. The boiler body is of a vertical cylindrical structure and is divided into a filler chamber and a 
water storage chamber through a supporting partition plate. The fume 
pipe is located on the middle lower portion of the 
water storage chamber. Heat dissipation fin plates are installed on the outer wall of the 
pipe, and the heat exchange area can be increased. An 
exhaust pipe is assembled to the upper portion of the filler chamber, so that 
smoke is exhausted upwards evenly. A water blocking cap is used for preventing water from entering the fume pipe. An inlet water 
distributor is arranged in the filler chamber, so that water is sprayed downwards evenly. Through a temperature-resistant filtering cotton plate, residual water in the 
smoke can be filtered out and returned back to the 
water storage chamber. According to the direct-heating hot water boiler, the one cavity design is adopted, the structure is compact, and materials are saved and are about one quarter those of an ordinary boiler; the size is small, the space is saved, the manufacturing cost is low, through the structure, secondary heat exchange can be conducted, and the heat efficiency reaches 97% or over; and 
smoke exhaust indexes are higher than national standards, the smoke exhaust temperature is lower than 50 DEG C, and the heat efficiency is greatly improved.