Chimney stove surround tiles series la nordica fiorella power type ambient air dependent heating power 6 kw efficiency 78 maximum room size 170 m flue connection top flue connection diameter 120 mm energy sources brown coal briquettes wood wood briquettes firewood coal exhaust gas temperature 380 c exhaust gas weight 56 mgs necessary pressure 0 10 mbar combustion systems primary air secondary air design 1 multiple flue connections safety