How Chimney Dampers Work
A damper is a plate or valve that closes the opening in your chimney when it isn’t being used. If you are having certain problems with your fireplace, such as smoke filling your home after you start a fire, it’s a good idea to learn how chimney dampers work. If you know how chimney dampers work, it will be easier for you to figure out what is going wrong with your fireplace.
The damper is an important part of your fireplace. A phenomenon known as the “chimney effect” refers to what happens when warm air rises up through a chimney flue, causing suction. The suction sucks even more warm air from the inside of your home. A closed chimney damper prevents cold air from flowing into the chimney, through the fireplace and into your home, increasing your heating bill. If a damper is left open when you are not using your fireplace, warm air from your home has a path to escape to the outside, also adding unnecessarily to your heating costs.
When a fireplace is being used, chimney dampers also keep fires from burning out of control by limiting the amount of oxygen accessible to the fireplace. An open fireplace damper allows the smoke from your fire to escape to the outside instead of being trapped in your home. If your house fills with smoke when you use your fireplace, this probably means the chimney damper isn’t being used correctly or has been left closed.
Most chimney dampers are at the bottom, or the throat, of the chimney. Throat dampers have a handle at the base of the chimney flue that you open before you start burning anything in the fireplace and close once you have finished using it. Other throat dampers are operated with a knob above the opening of the fireplace.
Some chimneys have top-sealing dampers at the top of the chimney. How chimney dampers work if they are top-sealing is with a handle inside the fireplace. The handle is attached to a cable that opens and closes the chimney damper.
It’s not difficult to understand how chimney dampers work, but understanding this makes it much easier to own and operate a fireplace.