The Anatomy of Your Chimney

What Keeps The Fire Burning?

During the winter months, many homeowners discover that they are having trouble with their chimneys and fireplaces. They may notice that their home is filling with smoke or that a strange odor is coming from the chimney. However, because they do not understand the anatomy of the chimney, they cannot begin to understand where the problem may lie. An understanding of the parts of a chimney can help homeowners properly care for and enjoy it. It will also assist your certified sweep during your annual cleaning and inspection, to be able to discuss options for improving efficiency and safety.

When thinking about the anatomy of the chimney, it is best to start with the flue. This is the long piece that most people picture when they think about the chimney and its main function is to allow smoke out of the home. In order to function properly, the flue should have a flue liner inside which will be made of steel, clay, or tile. Many homeowners prefer steel because it does the best job of protecting against water damage and because it tends to last much longer than the alternatives.

Chimney Anatomy Image - Columbia MO - Advanced Chimney

If smoke is pouring out through your fireplace, it can indicate a closed damper or something obstructing the air flow inside the chimney.

Inside of the flue, there should be a small piece called the smoke shelf. The purpose of the smoke shelf is to catch any foreign material that may begin to fall through the chimney. There is any number of dangerous things that could make their way into the chimney, from pieces of animal nests to leaves. The reason this is so dangerous is because these materials can be flammable and, in addition, they may clog the chimney, making it difficult for smoke to properly vent.

Also inside of the chimney is a very important structure referred to as the damper. This is the part of the flue that either closes or remains open, therefore either letting smoke out or keeping it in. When the fireplace is in use and a fire is burning, it is absolutely essential to make sure that the damper is open. If it is closed, the family will quickly know it because the home will start to fill with dark, dangerous smoke and, in some cases, poisonous gas.

When treated wood and coal are used to make a fire, they create a number of byproducts, including gasses, which can be extremely combustible and dangerous. In order to remain safe, they must be compressed so that a backdraft can be avoided. This is done by the smoke chamber. If the chimney does not have a working smoke chamber, the house may quickly become filled with gas and smoke.

Outside of the chimney, at the very top, is an important element called the spark arrestor. This is the piece of the chimney that keeps sparks from getting out. Even a small spark leaving the chimney could quickly escalate into a huge fire. Not only does this put the home at risk, but it poses a danger for the neighbors as well. When a fire starts on the roof, it can easily jump to a neighboring roof, starting a dangerous blaze there as well.

Also on the top of the chimney is the chimney crown, which protects the outer layer of the chimney and also keeps unwanted material from getting in. Not only does it keep out animal and environmental debris, but it also keeps moisture from rain or snow from getting in. If water enters the chimney, it can cause significant structural damage and may even lead to mold issues.

If a chimney starts to create odors or excessive amounts of smoke, there is a good chance that one of its many elements is malfunctioning. In order to figure out the problem quickly, homeowners should be familiar with the anatomy of their chimneys. To avoid major issues, be sure to have the chimney inspected each year before firing it up for the season.