Water Heater with Condensing Flue

A condensing flue water heater comprising:

• a water tank, having a lower dome and upper dome, and a cylindrical tank wall there between;
• a combustion chamber position under the water tank;
• a burner positioned within the combustion chamber;
• a straight cylindrical central flue of about 8 inches in diameter extending upwardly toward the upper dome but completely contained within the water tank the central flue having an inside diameter to which a multiplicity of rectangular metal fins are welded;
• a condensing flue connected in gas receiving relation to an upper portion of the central flue to receive all of the gas passing through the central flue, the condensing flue forming a helix extending downwardly from the upper portion of the central flue such the water drains freely from all portions of the condensing flue, the condensing flue extending through the cylindrical tank wall, to form an outlet, the helical flue being at least about 1½ in diameter inch tube;
• a water trap connected to the outlet leading to a drain;
• a fan in air receiving relation connected to the outlet and connected in air supplying relation to a vent;
• wherein the heat exchange capacity of the central flue is selected to be at least 75% of a heat transfer capacity of a combination of the central flue and the condensing flue.