"It's a kachelofen which is a type of masonry heater. Inside are baffles of firebrick to create an almost rocket stove type effect that makes combustion highly efficient. These can stay warm for almost a day after the fire has been put out. The two knobs are for 1) the flue, and 2) the fullness of the chamber. Not sure what the fullness one does.
The stove is designed to circulate warmed air through the firebrick lining of the chamber before exiting through the chimney, which comes out of the top of the stove, though I think it draws from the chamber lining.
I'm not sure if it is a downdraft design. It seems like it must be, but if so, it must be in a way that jives with the circulatory aspects as well. Not entirely clear on what path the air takes.
I do think it is designed to be lit once a day and get very hot. To me it seems logical that if there is a knob where you can specify the fullness of the chamber ranging from 1/4 to full, that the whole chamber is meant to be used. I don't see a reason there would be all that chamber if there was a firebox."
heittokuutio kuivia koivuklapeja=245kg
40 litraa halkoja = 15 kg
40 litraa x 16,3 = 1 heittokuutio
40 litraa x 27,3 = 1 pinokuutio