A chimney liner, as it sounds, is something that lines your chimney. It serves as a form of protection and is commonly made out of materials such as aluminum, metal, clay tile, and stainless steal. Because of the protection that a chimney liner provides, it is usually mandated by fire codes. So, what does a chimney liner actually do? It protects your home from both heat and combustibles. Did you know that a chimney fire can reach temperatures as high as 2,000 degrees Fahrenheit? By having a properly lined chimney you expand it's life by preventing the fire from deteriorating the inside. You also prevent your chimney from releasing harmful gases such as carbon monoxide into your home. A chimney liner will also help maintain proper venting performance, and possibly even improve the venting performance. If your chimney is without a liner or if that liner has any damage, it should be replaced by a professional who can choose the proper liner for your fireplace and install it correctly.