How Fireplaces Work

The Parts of a Traditional Fireplace

To understand how a traditional fireplace works, you'll need to know about its various components:

  • The hearth is built out of a fireproof material, such as bricks, and extends out beyond the fireplace.
  • The surround protects the walls around the fireplace and is often topped by a decorative mantel, perfect for hanging Christmas stockings or holding family pictures.
  • The firebox, the interior of the fireplace, contains the fire and collects the smoke.
  • The flue is the passageway at the top through which the smoke and gases travel for exit. Flues are often made of baked clay, but can also be stainless steel.
  • The chimney surrounds the flue, keeping its heat from contacting any flammable building materials that may have been used on the home.
  • The smoke chamber connects the fireplace and the flue. At the bottom of the smoke chamber is the smoke shelf, which deflects downdrafts and prevents any rain or soot from dropping directly into the fireplace.
  • Beneath the smoke shelf is the damper, a movable covering that separates the firebox from the space above. It prevents cold air from moving down into the house when no fire is burning. Some chimneys may also have a chimney damper, which is operated by a cable and closes the chimney at the top to eliminate downdrafts.
  • The spark arrester is a metal mesh that fits over the top of the flue and prevents the exiting gases from carrying burning materials onto the roof. A chimney cap prevents moisture and animals from entering the flue. It may rotate to block wind gusts.
  • Some fireplaces are equipped with an ash dump, an opening with a trap door where you can push the accumulated ashes into a pit below for later cleanout.
  • Fireplace doors can be made of glass or metal. They shut off the air flow when the fire has died down or the fireplace is not in use.

In the next section, we'll see how these parts work together to allow the fireplace to do its job.