Anatomy of a Chimney: Its Parts and Their Purpose

A chimney seems, at first glance, like a very simple structure. However, anyone who has one on his or her home should realize that they are actually quite complicated. There are many different parts to a chimney and all must be working properly in order to have a safe fire in the fireplace. Understanding the anatomy of a chimney and the purpose of each part is an important part of fireplace safety. And when you have your annual chimney inspection, you’ll be able to confidently talk with the sweep about any potential issues.

Chimney Sweep Graphic - Elkton MD - Ace Chimney Sweeps

Beginning at the very top, there is a piece on the chimney that is called the spark arrestor. A spark arrestor keeps sparks inside of the chimney, where they belong. A spark may be small but with the right wind current it can quickly turn into a blazing fire. This fire can spread throughout the home, onto the roof, and can even jump to neighboring rooftops. When the spark arrestor is not working, the entire neighborhood is at risk.

Another important piece found at the top of the chimney is the chimney crown. The chimney crown serves the important purpose of protecting the uppermost layer of bricks. It also helps keep foreign material, such as water or plants, from getting inside of the chimney and clogging it. It serves this function best when it is used in combination with a chimney cap, which also helps keep unwanted material out.

The uppermost important piece inside of the chimney is the damper. The damper is the part of the chimney that either opens it or closes it, therefore keeping smoke in or letting it out. When people notice that their chimneys are smoking during a fire, it is usually because they forgot to open the damper. Before starting a fire, be sure that the damper is open so that the home does not become dangerously smoky.

Another important piece found inside of the chimney is the smoke shelf. The smoke shelf is there to catch anything that might fall into the chimney. In some cases, it is needed to catch ash and in others it may catch leaves, twigs or even pieces of animal nests. If these things make their way into the chimney, it can quickly become clogged, which is dangerous. When the chimney is clogged, smoke and other dangerous gasses may become trapped inside the house.

When a fire burns in the fireplace, there are always combustible gasses created as a result. For this reason, it is important that the chimney has a working smoke chamber. The smoke chamber safely compresses combustible gasses and prevents a back draft. If it is not working properly, the gasses can create health and safety hazards in the home.

Although it may seem like a simple structure, a chimney is actually very complex. Understanding each of the parts is necessary to using the chimney and fireplace safely. If even one small piece malfunctions, the fire could quickly become dangerous. If it seems that there is a problem with any component of the chimney, it is important to have it repaired before making another fire.