Patent ID: 8402927

Claim:
A water heater comprising: a blower, which conveys combustible gas; a burner, which is connected to a combustible gas outlet opening of the blower; a heat exchange tank, which has an opening facing downward and comprises a base having a central portion from which the burner extends upward into the heat exchange tank to form a combustion chamber within an internal cavity of the heat exchange tank, a plurality of radially arranged flame tubes that have a cross section forming a wide flat tube extending downward from a top corner of the internal cavity, an exhaust gas discharge tube being set circumferentially of and separated from the base and in communication with the flame tubes for conducting flame gas in an upward-bent direction for discharging, and a water tank having an opening facing downward and having a tank diameter greater than the heat exchange tank, the water tank being partitioned to define a single partitioned space for water to be heated to flow therethrough and circumferentially housing the heat exchange tank and the downward-extending flame tubes arranged circumferentially around the heat exchange tank and received in the partitioned space of the water tank in a circumferentially spaced manner, the water tank forming a cold water inlet port in a lower side portion thereof and a hot water outlet portion in a central top portion thereof, wherein in operation, the burner carries out, along a circumference thereof, first-time heat exchange by heating an inside surface of the water tank, and then the burner carries out second-time heat exchange by heating an arc top portion of the water tank through ascending flame generated thereby, and finally, flame gas generated by the burner is guided by the arc top portion of the water tank to flow downward through the radially arranged flame tubes to carry out a third-time heat exchange, whereby thermal efficiency is remarkably increased.