Patent attributes
The present invention is directed towards a water heater having a combustion chamber and a water tank positioned adjacent to the combustion chamber. The water tank has a flue tube extending through or surrounded by the water tank and has an upstream end positioned to receive combustion gases from the combustion chamber and a downstream end positioned to exhaust the combustion gases. The flue tube also has a wall that extends between the upstream and downstream ends. The wall of the flue tube has an inner surface defining a combustion gas passage and an outer surface positioned to contact water received in said water tank. The walls have convolutions along at least a portion of their length and are configured to reduce laminar flow of the water adjacent the outer surface of flue tube, thereby providing increased heat transfer between the combustion gases in the flue tube and the water in the water tank.
