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The Anatomy of Your Average Chimney

Your chimney is an important part of your home. It is a structure that has a purpose and serves a specific function, but do you really understand how it works? Most people think that you just toss wood on the fire and gather around on a cold day. While this is certainly true, your chimney is working overtime to process the smoke as the fire is burning down below. In addition to providing heat, fireplaces offer a great deal of aesthetic appeal. In order to keep your fireplace and chimney in good working order, it is important to understand its anatomy.

Anatomy of Your Chimney

Before we talk about your chimney, it is a good idea to identify which fireplace you have installed in your home. There are factory fireplaces and masonry fireplaces. Masonry fireplaces are crafted out of brick and mortar while factory fireplaces are made from a metal firebox attached to a pre-built chimney. Depending on the model there may be additional features, but for now, we are going to stick to standard models.

Chase Top

While this may look like the cap, but is not, it is actually the part that encompasses and covers the top of the chimney. This part of the chimney is tasked with draining water and condensation away from the top so that it doesn’t pool.


This is the part that connects the chimney with the fireplace. They are in the top part of the firebox and will close when there is no smoke to vent to the outside. You can activate it with a pulley or lever, and keeping them closed correctly will prevent energy loss.

Chimney Cap

This is most often found in prefabricated chimneys. This attachment sits at the top of the opening of the flue. It helps to keep the rest of the chimney safe from water damage. It will stop rain and other moisture from settling into the cracks and it will also keep nosey critters from climbing down the chimney. In mason work, this is referred to as the chimney crown.

Smoke Chamber

Commonly found on masonry fireplaces, this helps to shuttle gas from the firebox into the flue. The slop is crafted in a way that will ensure the gas is gently compressed to prevent a backdraft.


This part of the chimney is on the inside. It is a duct that takes the products of combustion and transfers them outside of the home. It is critical that your flue liners are structurally sound to keep your substrate safe from corrosion and heat.

Chimney Chase

This is the most visible part of a chimney. You can cover it in a variety of materials to make it visually pleasing or even to match the decor of a home. It is tasked with concealing the flue in the chimney.

How A Chimney Works

The purpose of your chimney is to vent smoke from the combustibles used in your stove or fireplace. The gas and smoke will rise up through the draft and flow process. The more flame in your fireplace, the higher the warm gas will rise in the flue and cold air outside will be pulled down to encourage combustion. The pressure in your chimney on the inside of your house needs to be monitored to prevent improper flow.

The main things that affect the draft and flow process, specifically the pressure is the air movement in the home, the amount of air in the space, and how much competition there is for cold air outside the chimney. If you have windows open, or if your home is not properly insulated, it can lead to poor chimney performance. This can be as simple as a fireplace that doesn’t produce much heat to copious amounts of smoke blowing back into the house instead of venting outside. Understanding the anatomy of your chimney is the best way to ensure that you operate your fireplace in a way that allows it to work efficiently.