Patent ID: 9004018
Filing Date: 2015-04-14
Classification: F24H

Abstract:
1. Fuel-fired liquid heating apparatus comprising: a tank adapted to hold a quantity of liquid to be heated, said tank having upper and lower ends; a primary flue longitudinally extending vertically through the interior of said tank, said primary flue extending between and being connected to said upper and lower ends of said tank; a secondary flue longitudinally extending vertically through the interior of said tank, said secondary flue having a total surface area exposed to the interior of said tank, an upper non-coiled end portion coupled to said primary flue adjacent said upper end of said tank and further having a vertically coiled lower end portion extending downwardly from said upper non-coiled end portion, with the entirety of said vertically coiled lower end portion of said secondary flue being disposed in a lower portion of said tank; and a fuel-fired combustion system operable to flow hot combustion products sequentially through said primary flue and said secondary flue to transfer combustion heat therethrough to liquid disposed in said tank,