Patent ID: 7836856
Filing Date: 2010-11-23
Classification: F24H,Y02B

Abstract:
1. A condensing flue water heater comprising: a water tank having a lower dome and an upper dome, and a cylindrical tank wall extending therebetween; a combustion chamber positioned under the water tank; a burner positioned within the combustion chamber; a straight cylindrical central flue of at least 4 inches in diameter extending upwardly toward the upper dome but not passing through the upper dome, the central flue having an inside diameter to which a multiplicity of rectangular metal fins are welded; and 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, wherein the number and arrangement of the metal fins in the central flue is selected so that a heat exchange capacity of the central flue is about 75% to 93% of a heat transfer capacity of a combination of the central flue and the condensing flue.