Chimney liners are used to protect the inside of a masonry chimney from wear and tear caused by wet conditions. Moisture, over time, will cause decay and corrosion of mortar, clay, and brick liners. How? Moisture reacts with the exhaust gases to form an acid that slowly "eats away" at the chimney. Moisture can also collect and seep into cracks, mortar and bricks. In colder climates, this moisture will freeze, expand and then thaw, causing chunks of the chimney to break and crumble. There are also times where moisture can actually drip back into your appliance causing the unit to corrode or rust. Chimney liners also reduce the size of the flue opening, which is important for venting appliances with low stack temperatures (a characteristic of today's higher efficiency appliances). Smaller flue openings require less heat to create the chimney effect which draws combustion byproducts to the outside. These chimney liners are constructed of stainless steel, which are used with appliances that operate on all fuel types including wood, oil and gas. These relining kits are available in a variety of diameters and lengths to fit your needs.