What Is a Chimney Damper?

A chimney is actually a complex system comprised of multiple components, one of which is the damper. This metal spring door is located at the top of the chimney or above the fireplace. An attached metal chain runs down the chimney, allowing the user to open and close the chimney from inside the house. When the damper is closed, warm or cool air is kept inside the home, conserving energy use.

Diagram courtesy of the CSIA

If the chimney does not have a damper, at least one-quarter of the energy used in the home is literally going up the chimney. The damper enables the chimney flue to close when the fireplace is not in use. The air generated by a central HVAC system remains inside the home instead of being funneled up the chimney.

A damper also prevents insects, birds, and small animals from entering the chimney. Water and other debris are kept out of the chimney when the damper is closed. If a damper was not included when the fireplace was built, it can be installed later. The best dampers are made from material that will not rust, extending their lifetimes.

Since the damper can only be seen by looking up or down the chimney, many people forget it exists. This causes some to start a fire without first opening the damper. The result is a lot of smoke in the home and no flame in the fireplace. At some point, this is bound to happen but fortunately, opening the damper will remove the smoke.

Spend the money to have a chimney damper installed because it will quickly pay for itself in reduced energy costs. Select a non-rusting damper, not a cheap version made from inferior materials. Have a professional install it and conduct a chimney inspection in the process to verify that the system is not in need of repair.