Creosote, the black or brown residue of combustion that collects within the interior surfaces of the chimney flue liner, is very flammable. If permitted to Construct up, it may possibly capture fire, creating cracks in "fireproof" brick, stone or clay flue liners and permit heat to succeed in nearby wood framing https://gasfireplaceinsert09641.blogunok.com/28321589/helping-the-others-realize-the-advantages-of-wall-mounted-electric-fires