Slow combustion stove chimney stove surround ceramic series la nordica gisella power type ambient air dependent heating power 8 kw efficiency 78 maximum room size 229 m flue connection top flue connection diameter 130 mm energy sources wood firewood co emission under 01 exhaust gas temperature 350 c exhaust gas weight 73 mgs necessary pressure 0 12 mbar combustion systems primary air secondary air design 1 multiple flue connections s