US 4,856,491 AGranted

High efficiency solid fuel burning stove

AssigneeVermont Castings, Inc.

InventorsRobert W. Ferguson, Derik K. Andors

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Abstract

A solid fuel heating apparatus including a secondary combustion chamber in gaseous communication with a primary combustion chamber for increasing heating efficiency and for reducing polluting emissions. The secondary combustion chamber is lined with a refractory material. The entrance to the secondary combustion chamber is disposed at the bottom thereof adjacent the grate, and the grate containing the fuel is sloped at an acute angle with respect to the vertical to cause charcoal to accumulate adjacent to the orifice and to cover the entrance orifice of the secondary combustion chamber. Exhaust gases drawn into the secondary combustion chamber must first pass through the charcoal so that they are preheated prior to being mixed with secondary air. Means are provided for metering secondary air into the entrance orifice to cause mixing of the secondary air with the exhaust gases when the exhaust gases are at their maximum temperature. Refractory baffles are disposed within the secondary combustion chamber to enhance mixing of the combustion gases and to reradiate heat into the combustion gases. The baffles are vertically aligned at the bottom to reduce flow restrictions but still cause significant mixing, and are curved at the top to focus the gases into a choke zone. The side walls of the stove are insulated to contain heat within the primary combustion chamber.

Claims21

Dependent claims

A heating apparatus for burning solid fuels comprising:

a frame assembly enclosing a primary combustion chamber for burning a supply of solid fuel contained therein, said frame assembly including a front wall, two side walls, a rear wall, a top and a bottom;
a grate for carrying a supply of solid fuel contained within said primary combustion chamber, said grate being disposed at an acute angle with respect to a selected one of said front, side and rear walls for promoting the accumulation of charcoal formed from combustion of the solid fuel against said selected one of said walls at a bottom end thereof;
and
a secondary combustion chamber in gaseous communication with said primary combustion chamber for removal of pollutants from exhaust gases exiting said primary combustion chamber, said secondary combustion chamber comprising:
an entrance orifice disposed in said selected one of said walls at a bottom end thereof closely adjacent said grate, whereby said entrance orifice may be covered by charcoal during operation of said apparatus whereby exhaust gases exiting said primary combustion chamber into said secondary combustion chamber pass through charcoal;
means for metering secondary combustion air containing oxygen into said entrance orifice for mixing with exhaust gases exiting from said primary combustion chamber;
baffles arranged to enhance mixing of said combustion gases with secondary air to promote the more complete burning of pollutants, each of said baffles comprising a generally vertically oriented lower portion and an upper portion, said lower portions of said baffles being generally parallel to one another and said upper portions of said baffles having surfaces which are non-parallel and converging with respect to one another for causing convergence of exhaust gases and secondary combustion air;
and
means for venting the exhaust gases from said secondary combustion chamber to an exhaust pipe.

6 more elements

A heating apparatus for burning wood fuel comprising:

a frame assembly enclosing a primary combustion chamber for burning of a supply of wood contained therein, said frame assembly including a front wall, two side walls, a rear wall, a top and a bottom;
a secondary combustion chamber disposed within said frame assembly adjacent a selected one of said front wall, said side walls, and said rear wall, said secondary combustion chamber having a bottom end disposed adjacent said bottom of said frame assembly;
a sloped grate for carrying a supply a wood contained within said primary combustion chamber, said grate being disposed at an acute angle with respect to said selected one of said walls for promoting the accumulation of charcoal formed from combustion of wood against said selected one of said walls at said bottom end of said secondary combustion chamber;
an entrance orifice disposed in said selected one of said walls for providing gaseous communication between said primary combustion chamber and an interior of said secondary combustion chamber, said entrance orifice being disposed on said bottom end of said secondary combustion chamber closely adjacent said grate, whereby said entrance orifice may be covered by charcoal formed by combustion during operation of said apparatus whereby exhaust gases exiting said primary combustion chamber into said secondary combustion chamber pass through charcoal;
means for metering secondary air containing oxygen into said entrance orifice for uniform mixing of secondary air with exhaust gases drawn into said entrance orifice from said primary combustion chamber;
refractory baffles disposed within said secondary combustion chamber for promoting mixing of said combustion gases, each of said baffles comprising:
a lower portion, said lower portions of said baffles being generally parallel to one another and generally aligned in a vertical direction;
and
an upper portion, said upper portions of said baffles having non-parallel, converging surfaces for focussing gases passes therethrough into a narrowed choke zone;
and
means for conducting gases exiting from said secondary combustion chamber to an exhaust pipe.

8 more elements

Dependencies are inferred from the claim text.