Just so we have our chimney terminology straight, here is a labeled diagram of the parts of a fireplace and chimney.
Ash Chute: A hole in the floor of the firebox that you can sweep ash and burnt debris into. It is often connected to a pocket area below the firebox of in the basement that has an small metal exterior door for removal of fireplace ash.
Crown: The crown of the chimney is the flat surface at the top of the chimney structure. This is also the platform on which the chimney cap sits.
Damper Door: This is a metal door that pivots and open and closes. Sometimes it has a hinge and sometimes it is just a metal flap setting in place by gravity. They can be cast iron or sheet metal. Homeowners often call the damper the “flue” or “flume” but in fact the flue is the hole that the damper is closing off.
Damper Frame: This is the metal frame that is mortared in place and is immovable. The damper door connects against this frame. The frame can be sheet metal or cast iron.
Firebox: This is the open mouth area of the hearth that you put the logs and have the fire.
Flue Tile: This is the area of the chimney where the walls are parallel and the chimney makes a long run to the chimney top. It is often lined with a clay flue tile, or a metal flue liner. Sometimes it is just bare brick.
Fresh Air Inlet: This is not shown on our diagram. But this is a vent on the side or back wall of the firebox that vents through the wall to the outside. These are designed to give the firebox plenty of outside combustion air while you have a fire burning.
Lintel: This is the top lip of the fireplace hearth opening. If you are setting a log in the firebox and you hit your head on the bricks above your head… that is the lintel.