A fireplace damper is a metal plate that regulates the flow of air into and out of a fireplace through a chimney. Another important function of the damper is to prevent heated air from escaping a house when the fireplace is not in use. In larger buildings, dampers help regulate the temperature in different rooms by controlling airflow. In most cases, dampers in residential buildings are manually operated by turning a knob or pulling a chain attached to the damper.
Bolt the two steel hinges to the edges of the rectangular steel frame using two of the 4-inch steel bolts and the adjustable ratchet. Attach the hinges in the middle of the long edges of the steel frame.
Attach the rectangular steel plate to the hinges using two of the 4-inch steel bolts and the adjustable ratchet.
Use the electric drill to bore two holes in the sides of the chimney approximately 2 feet above the fireplace. Also bore two holes into each of the long edges of the steel frame directly below the hinges.
Attach the rectangular steel frame to the inside of the chimney by inserting the two 8-inch concrete screws through the bored holes in the edges of the steel frame and into the bored holes in the chimney.
Seal the rectangular steel frame in place by coating the edges of the frame with rubber cement.
Bolt each piece of the steel-linked chain to either edge of the rectangular steel plate. Pull each chain down to make sure the rectangular steel plate opens and closes properly.
You can order the rectangular steel frame and plate from a chimney supply company or an industrial supply company such as Grainger. You can purchase the other components at a hardware store. Make sure the rectangular steel frame is properly sealed with the rubber cement. If it is not sealed correctly, cold air will enter the house through the chimney, resulting in a draft. Use two coats of rubber cement if necessary.
Always keep the damper closed when the fireplace is not in use. Doing so will prevent cold air (as well as animals and debris) from entering the house through the chimney.