Lined or Unlined?

THAT is the question.
Whether your new or old to chimney service you may not know the anatomy of a chimney. For a fireplace structure you have the usual suspects, firebox, lintel, throat, smoke chamber and then progressing up you have your flue. Although all these areas are essential and work together as a “fireplace system”, I would have to say that the most important, is the flue. The flue’s only function is to carry the gases of combustion up and out. Similar to an exhaust in a car, which purpose is to keep the fumes away from the engine and passenger compartment.
Optimally, your flue will be lined. Clay tiles have been used as liners during construction dating back to the early 1900s. Tiles were a great addition because it added another layer of protection for exhaust, and insulated the chimney protecting the chimney walls from heat. However, not all chimneys were built this way.
An unlined flue will have no barrier to the brick and mortar. smoke, carbon and tar particles can escape through the compromised brick or mortar joint. Even if you can’t see the transfer you may be able to smell it. In an upstairs bedroom or perhaps you’re in the city and your upstairs neighbor is smelling smoke. That shouldn’t happen with a properly drafting fireplace.
It’s just as important, if not more, to address holes in furnace flues. Those oil and gas fumes can enter the living space through defects in your liner. You can also burn more fuel if these defects are not addressed! Think of it as a straw with a hole in it. The draw is not optimized and will cause the heating appliance to overwork. That is a regular stream of extra money leaving your pocket.
Even if your chimney was built with tiles, after many years of use, deterioration will happen. Rainwater can also enter this area acerbating the affect. Regular chimney inspections, as recommended by the Nation Fire Protection Agency, will keep you ahead of the chimney game. That’s a win in my book.

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