High efficiency combustion heater

摘要

A furnace or furnace-and-pot heating system comprises an inner shell, an outer shell surrounding the inner shell to form a duct between the two shells for preheating combustion air flowing down the duct to enter a combustion chamber within the inner shell. A container or pot for heating material such as water or foodstuffs may be supported inside the inner shell and above a combustion zone, such pot to be of diameter to form with the inner shell an annular flue for escape of combustion products. Draft control means are provided to regulate the amount of combustion air entering the combustion chamber.