Abstract: A secondary combustion system for a wood burning stove employs an insulated passageway which is configured to substantially increase the turbulence of an exhaust stream passing therethrough. The insulated passageway comprises a generally transversely extending portion and a generally vertically extending portion. The passageway is configured to impart a rotation to the passing exhaust stream in one direction and to successively impart a rotation in the opposite direction. The insulated passageway comprises a plurality of helically extending channels. The passageway is also configured to have an increasing cross-sectional area to insure sufficient residence time for effecting the secondary combustion of the exhaust gases.

Abstract: A secondary combustion system for a woodburning stove employs a concave shaped screen for dispersing exhaust gases. A mixing chamber is formed in an insulated conduit between the concave screen and a second planar screen. The planar screen is perforated to form a random array of flaps which increase the turbulence of the exhaust stream so that a secondary combustion of the exhaust gases is produced.