Chimney stove surround steel series la nordica fortuna power type ambient air dependent heating power 7 kw efficiency 80 maximum room size 200 m flue connection top flue connection diameter 150 mm load front energy sources wood firewood exhaust gas temperature 292 c exhaust gas weight 54 mgs necessary pressure 0 12 mbar design 1 multiple flue connections safety features self closing door 1 point door lock combustion chamber ironker fe