Abstract: A pellet burning stove includes a firebox defining a combustion chamber, a pellet burner located within the firebox, a feed system for moving combustible pellets to the pellet burner and an ash pan for receiving ashes from the pellet burner. The pellet burner includes a horizontal surface having an elongated combustion zone defined by a plurality of primary air openings in the burner surface, and a feed surface adjacent to the combustion zone. The feed system moves a thin layer of combustible pellets across the feed surface into the combustion zone. An air plenum surrounding the feed surface of the pellet burner supplies combustion air upwardly through the primary air opening and the layer of combustible pellets. The air plenum maintains the pellets relatively cool until they reach the combustion zone. Ashes drop off an edge of the burner surface into an ash pan. An artificial log set and a log support member fabricated of refractory fiber material define a secondary combustion cavity above the pellet burner.

Abstract: Solid fuel heating appliance having high thermal efficiency and low levels of polluting emissions. The heating appliance includes an insulated secondary combustion chamber where a mixture of exhaust gases from the primary combustion chamber and secondary air is burned. A catalytic igniter is provided in the secondary combustion chamber to lower the ignition temperature of the unburned volatile gases from the primary combustion chamber. Regenerative feedback structure is provided in heat exchange relationship with the exhaust from the secondary combustion chamber to preheat the mixture entering the secondary combustion chamber, catalytic igniter, and the regenerative heat transfer assure substantially continuous combustion within the secondary combustion chamber even when conditions in the primary combustion chamber change.

Abstract: Exterior retrofit system for attachment to wood or coal-burning stoves including a secondary combustion chamber and a catalytic igniter. The secondary combustion chamber is lined with refractory material and is arranged to preheat flue gases emanating from the woodburning apparatus before ignition at the catalytic igniter. The refractory walls have an undulating structure to increase mixing and residence times for more complete burning. Provisions are made for introducing additional combustion air into the secondary combustion chamber. Combustion performance is improved resulting in reduction of cresote deposits and particulate emissions and reduction in the amount of fuel consumed for a given heat output. The retrofit unit is self-contained and requires no permanent or complicated modification to the stove. This system also has application for use on the interior of a stove, both as a retrofit and as the basis for a specifically designed stove.

Abstract: Woodburning heating apparatus including a catalytic igniter for increasing heating efficiency and reducing polluting emissions. The apparatus includes a secondary combustion chamber in gaseous communication with a primary combusiton chamber. The secondary combustion chamber is lined with a refractory material and includes a perforate catalytic igniter through which combustion gases from the primary combustion chamber flow. The secondary combustion chamber further includes refractory baffles arranged to enhance mixing of the combustion gases and located to re-radiate heat onto the catalytic igniter. Preheated secondary combustion air enters the secondary combustion chamber so that the combustion gases are more completely burned to improve heating efficiency and reduce emissions.