Your chimney is responsible for venting gases produced from fuel out of your home and into the atmosphere. Fuels such as propane, oil, kerosene, natural gas, and wood all produce flue gases that must be vented into a chimney. In order for these gases to be expelled into the atmosphere, there must be proper drafting of the chimney.
Chimneys can have three types of interior liners, made of different materials: clay, ceramic, or metal. These liners help to direct the flue gasses into the outside atmosphere. Chimney liners are also responsible for stopping lethal carbon monoxide gas from seeping into your home. They do this by preventing hot embers in smoke from entering through a crack in the flue, which can potentially cause materials in or around the chimney to ignite.