The invention discloses a water heating apparatus. The water heating apparatus comprises a furnace core, a furnace body and a centrifugal blower; the furnace body is a hollow column structure in an upright posture, the interior of the furnace body is cylindrical furnace chamber, the furnace core is provided coaxially in the furnace chamber, and a flame-passing gap is provided between the furnace core and the inner wall of the furnace chamber; the centrifugal blower is supported at the upper end of the furnace body, an air outlet cylinder of the centrifugal blower extends into the furnace chamber; a waste gas discharge outlet is provided at the bottom end of the furnace chamber, the waste gas discharge outlet is connected with a smoke discharge pipeline; and a first furnace core, a second furnace core, a third furnace core and a fourth furnace core are hollow heat-resistant thin-wall structures and are filled with flowing water, therefore burning liquid carried on the second furnace core, the third furnace core and the fourth furnace core cannot cause boiling phenomenon, result in that the combustion of the fuel is more stable, and the phenomenon of boiling splashing is avoided.