Has your chimney sweep told you that you need a new flue liner? It is possible, after an inspection, that your chimney pro will recommend a replacement.
Flue liners are important, since they reduce the risk of carbon monoxide leaking into your home, protect the chimney from creosote buildup (a natural residue from burning wood that can cause chimney fires), and increase its life.
Many older fireplaces were built with clay flue liners, or sometimes none at all. Over time, these liners will become cracked and damaged, enabling the creosote to dissolve the mortar, soak into the joints, and cause a fire. The National Fire Protection Association (NFPA) recommends annual inspections to make sure your liner is in good shape, and that clay liners be repaired or replaced when cracked or damaged.
Most replacements or upgrades to your chimney flue liner are made using stainless steel liners, which require less labor and are available in more sizes and types to correctly fit the needs of your particular fireplace or woodstove. Insulation should be installed between the liner and the chimney. This maintains consistent higher temperatures in the flue, which minimizes creosote buildup and keeps heat from damaging the structure of your home.
Cast-in-place liners are by far the most costly per square foot, though they are great for shoring up an old chimney whose structure is in question. They are stronger and burn cleaner than metal or clay, but can be very challenging and costly to install or remove.
Professional installation of your flue liner—whether metal, cast-in-place or clay—is important. Replacing or installing a flue liner is a difficult process and must comply with NFPA safety codes. When installed properly, flue liners are highly efficient, safe, and durable, and should provide you with peace of mind and many more enjoyable evenings by the fire.