This invention relates, in general, to an improvement in wood burning stoves and, in particular, it relates to a method and apparatus for increasing the efficiency and safety of wood burning stoves.
Due to the relative scarcity and high cost of petroleum products, wood burning stoves have been increasingly employed for home heating and other purposes. A reasonably air tight wood burning stove is far more efficient than a home fireplace, which may result, in fact, in a net energy loss. However, wood burning stoves presently being utilized suffer from three significant drawbacks. First, wood burning stoves represent a severe fire hazard since the wood fuel therefore contains volatile substances which are normally not oxidized during combustion. These volatiles will burn if mixed with air at temperatures in excess of 590.degree. C. However, the typical wood burning stove operates within a temperature range of between 230.degree. and 370.degree. C. At these temperatures, these volatile substances, known generally as cresote, remain unoxidized and tend to adhere to the flue pipes and are a cause of not infrequent chimney fires. Secondly, the incomplete combustion of the carbonaceous fuel in wood burning stoves leaves the unoxidized residue as a pollutant and an environmental hazard which is discharged to the atmosphere. Third, the unoxidized residue represents a loss of overall combustion efficiency. While claims have been made to efficiencies greater than 65% in some wood burning stoves, independent testing laboratories have determined that the combustion efficiency of typical wood burning stoves lies in the range of between 50 and 65%. One possible solution to the aforementioned problems is to increase the combustion temperature of the typical wood burning stove by providing additional air into the combustion chamber so as to create temperatures high enough to bring about complete combustion. Variations on this technique date back to the 18th century with the Franklin stove, wherein the volatiles are mixed with additional air in the combustion chamber in order that temperatures high enough to bring about complete combustion may be obtained. These efforts have only been partially successful.