WOOD BURNING HEATING UNIT

摘要

An improved wood burning heating unit (10) which possesses a trapezoidal housing (10) including a fire box (26) portion possessing in a combustion zone a fire brick grid (30) for supporting fuel wood. An air duct (23) extends beneath the fire brick grid (30), upwardly along a back portion of the heating unit (10), and terminates in fluid communication with a helical heat exchanger section (68). The heat exchanger section (68) surrounds a central chimney (34) including an open upper end and an open lower end selectively closable by a damper (42). An outside air T connection includes a first leg connected to an outside air inlet, a second leg communicating with the chimney (34), above the heat exchanger section (68), and a third leg (84) connected for directing combustion air to the fire box (26). The outside air T connection also includes a pair or air pressure actuated flapper valves (78 and 80) for regulating combustion air flow depending upon conditions within the fire box (26). In operation, combustion air flows from the outside air inlet to the fire box (26) and combustion gasses flow upwardly over a fireback (33), downwardly through a hollow air flow space behind the fireback (33), through and below the fire brick grid (30), upwardly through the exhaust conduit (24), through the helical heat exchanger (68), and outwardly to ambient through the central chimney (34). A bypass damper (42) in the chimney (34) allows direct exhaust of combustion gasses during start up.