Removing a fireplace damper is a common part of a chimney renovation that homeowners come across. Often times there isn't enough room to pass your stainless steel chimney liner through the damper opening, so you may need to remove the fireplace damper or at least a portion of it, when connecting a wood stove or insert. The damper is commonly referred to as the flue, however it is actually the access point to the flue. Understanding the different components of the damper will help explain how to remove it.
A fireplace throat damper is comprised of two main components: the Frame and Flapper. The damper frame is fabricated from heavy cast iron or steel and has an opening that allows the smoke to travel up through the chimney. The opening in the frame is typically 3" to 8" wide and 24" to 36" long. The frame is mortared in place just below the smoke shelf. The other main component is the Flapper. The Flapper allows you to control the draft, by letting more or less air to flow through the chimney flue. This operation is regulated by the use of a handle or chain pulley.
Removing the Damper Components
Every damper has a pivot point where the chain or handle will allow the damper to open or close. Locate the pivot point and see if the damper flapper can be lifted out of the guides. If you are unable to lift the flapper out of the guides, you will need to cut them out using a grinder with cut off wheel. The handle that is connected to the flapper is usually bolted to the top of the firebox, right behind the lentil. The lintel is a heavy piece of angle iron that holds up the brick over the center of the fireplace and is embedded into the brick, located just above the opening in the firebox. Usually the bolts are rusted and seized, so you may have to use a grinder wheel to cut them off.
The frame of the damper is a bit more difficult to remove. The frame is usually much thicker that the flapper. You can go about removing the frame in several ways. You could either remove the frame by cutting out the metal, or loosening the mortar around the bricks around the frame. If your frame is cast iron, using a hammer will sometimes shatter the frame. Using an angle grinder and cutoff wheel or sawzall is another option, it is a good idea to have an extra supply of wheels or blades. Those of you that are skilled and confident enough to use a cutting torch, may wish to use it. You could also use a chisel and hammer to loosen the frame around the brick.
When removing a throat damper please make sure to have all the appropriate safety equipment. Eye protection, gloves, fire extinguisher and a good size cover to help keep everything clean and protected. Removing the damper can be a dirty job, however the dirty jobs are the ones that can save you hundreds even thousands of dollars.