Heat-recovering apparatus for furnaces

In a hot air furnace for a dwelling unit a flue gas heat exchange device located within an exhaust gas discharge flue wherein said heat exchange device preheats combustion air that is directed to the combustion chamber of the hot air furnace wherein the improvement comprises:

• a flue gas heat exchanger that comprises an extended inner duct that conveys the exhaust flue gases in heat exchange relationship with a jacketing chamber surrounding the inner duct, said inner duct having a one piece angular bent deflector strip that extends the length of the inner duct to retard the flow of exhaust flue gases and to enhance the heat exchange between the flue gases within the inner duct and the jacketing chamber, said jacketing chamber defined by a wall extending around the inner duct and having an air inlet and air outlet at a common end of the jacketing chamber, said air inlet is in communication with exterior air through a connecting duct that terminates on the under side of the jacketing chamber, said air discharge is in communication with the hot air furnace combustion chamber through a connecting duct that terminates on the top of the jacketing chamber above said jacketing chamber air inlet, within said jacketing chamber extending from the inner duct are pairs of radially mounted fins that extend longitudinally from the common end of the jacketing chamber but not touching the opposite end of the jacketing chamber, said jacketing chamber further containing two splitter fins that extend between the outer wall of the inner duct and the inner wall of the wall spaced from the outer wall of the inner duct to define an upper and lower jacketing chambers at the common end of the jacketed chamber, said splitter fins extending longitudinally within the jacketing chamber of the same length as said pairs of fins, said splitter fins defining an air flow path within the jacketing chamber where inlet air is directed to the lower jacketing chamber inlet, longitudinally down the lower jacketing chamber, up to the upper jacketing chamber longitudinally down the upper jacketing chamber and out the jacketing chamber air outlet.