Bergslag chimney
The Bergslag chimney is a cylindrical type of stove made of thick cast iron that has been manufactured since the 17th century. The designation “ chimney ” does not correspond to today's common usage because of the invisible fire.
The name comes from the Swedish historical province of Bergslagen , where most of the ovens of this type were made. Today you can still find a large number of functioning specimens that are between 100 and 150 years old. The oldest dated Bergslag chimney dates from 1675. Carl von Linné described in his Västgöta trip in 1746 that he had found a large number of "round iron tiled stoves" in the village of Brattforshyttan . The Bergslag chimneys were often made in small, local ironworks and their casting technique was similar to that of cannon barrels. It is believed that the Bergslag chimney is the oldest cast iron stove in the world that is still in practical use.
Apart from its round shape, typical of the Bergslag chimney is the double-angled flue gas pipe , which is also made of strong cast iron. As a result, the flue gases have a longer way to the chimney and the heated flue gas pipe thus contributes to additional heating of the apartment, a simple method to increase the effectiveness .
The function of this stove is simple. Only dry wood is burned in the cylindrical furnace. There is neither a grate nor an ash box . The large, iron stove door also allows quite large logs to be heated. It has a small air inlet, the chimney has a throttle valve, and there are no other regulation options. Nevertheless, the Bergslag chimney is quite effective because of its closed nature. Measurements have shown that the combustion of 5 kg of wood in one hour produces a heating effect of approx. 7,000 watts , which corresponds to an efficiency of 60 to 65%. The flue gases have a low temperature of approx. 180 ° C and the thick-walled cast iron helps to store the heat to a certain extent. Even after the fire went out, the fireplace gave off heat for some time. A Bergslag chimney with a flue gas pipe weighs around 250-300 kg.