What is a flue liner?
A flue lining in a masonry chimney is defined as “A clay, ceramic, or medal conduit installed inside of a chimney, intended to contain the combustion products, direct them to the outside atmosphere, and protect the chimney walls from heat and corrosion.” Although building codes vary from state to state, and city to city, in the DeKalb area flue liners are required to meet code.
Flue liners are required when upgrading your furnace to an 80% AFUE because there is less heat going up the masonry chimney and when the temperature reaches around 130 degrees the flue gases turn from a gas to a liquid that is corrosive to your chimney. If you have a 90% or greater efficiency furnace installed and the only appliance vented in the masonry chimney is a water heater you still need a liner installed to prevent ruining your chimney.
Liners protect the masonry from the corrosive byproducts of combustion. In the tests it was determined that if the flue gases were allowed to penetrate to the brick and motor, the result would be a reduction in the usable life of the chimney. The flue gases are acidic in nature and literally eat away at the motor joints from the inside of the chimney. If you see white streaks on the outside of your brick chimney or bricks missing, or no metal liner coming out of top of the chimney like the picture above you may need to call All-Star Heating & Air Conditioning Inc. to correct your problem before it’s a more expensive repair.