The Purpose of a Chimney Damper


If you have a woodstove or open-hearth fireplace in your home, you’re familiar with your chimney’s dampers. It’s one of the few working components of a fireplace that you have to know how to use when lighting a fire. Have you ever wondered what exactly the purpose of the damper is? And how does it work?

What is a chimney damper for?

Your chimney is a hollow tube that travels from your fireplace straight up and out of your roof. That hollow tube can let air flow freely out of your home and cold drafts to find their way in on blustery days. The chimney damper is meant to stop that flow of air. In fact, having the right damper in place can actually save you money on your home energy bills by lowering the amount of warm air that’s lost through your chimney when the fireplace isn’t in use.

Where is the chimney damper located?

In most chimneys, the chimney damper is located directly above the firebox, at the base of the chimney throat. There are some specialized fireplace dampers, however. Top-sealing chimney dampers have become an increasingly popular option, as they form a complete seal around the chimney opening when the damper is closed to prevent moisture, air, and debris from entering the chimney flue.

How do chimney dampers work?

If you have a traditional chimney damper, the mechanics behind the damper is relatively simple. There is an outer metal rim and an inner metal flap. When the damper is closed, the flap will cover the entire chimney flue to prevent the exchange of air between your home and your chimney. When the damper is open, the damper flap twists or lifts out of the way to allow smoke to escape through the chimney. If you have a top-sealing chimney damper, either a flap on the damper will open to allow smoke out, or the entire damper will rise up and off of the chimney on a hinged framework when the damper is open.

Can dampers break?

Yes, dampers can break and become stuck either completely open, completely closed or somewhere in between. Another common damper problem is warping. Because the chimney damper sits right on top of the firebox, it deals with a lot of heat. The extreme heat of the fire can cause the metal to warp, as can moisture that makes its way down the chimney. When the chimney damper warps, the damper flap will fail to form a complete seal when closed. This allows warm air to escape from your home even when the damper is closed. Additionall, it can allow cold air to draft in.

What do you do when a chimney damper breaks?

When chimney dampers warp or break entirely, a top-sealing damper is usually recommended as a replacement. That’s because it can be difficult to get into the chimney flue to replace a damper in the chimney throat. It’s also because top-sealing dampers do a better job of closing off the chimney flue and keeping water out.

If your chimney damper is giving you problems, call Your Chimney Sweep in Indianapolis IN! We can evaluate your existing damper and install a replacement damper when needed!