Hot water unit

The invention provides a hot water unit comprising a direct contact type heat exchanger (2), a total heat exchanger (3), a liquid distribution device (4) and a furnace pipe (5). The liquid distribution device (4) distributes hot water in the direct contact type heat exchanger (2), heat exchange is conducted directly between the hot water and smoke discharged by the furnace pipe (5), and the heatedhot water is conveyed to a heat user through a hot water outlet (7). The cooled smoke enters the total heat exchanger (3) through a smoke discharge connecting pipe (12), total heat exchange is conducted between the smoke and air coming in from the external environment, the heated and humidified air is conveyed to the furnace pipe (5) to serve as combustion air through an air pipeline (11), and the cooled and dehumidified smoke is discharged through a smoke outlet (13). Combustion temperature is lowered while smoke waste heat is recovered, and NOx emission is reduced. the structure is simplified, corrosion is avoided,