Chimney dampers allow you to close the chimney flue when the fireplace is not in use to prevent heated or cooled air from escaping the home through the chimney. An open flue is an invitation for inefficient climate control and added problems due to prolonged exposure of the chimney to the elements.
Installing a lock top chimney damper can be a great way to prevent any energy leakage from your home caused by a chimney. Chimneys can be a major factor in losing heat in the winter and air conditioning in the summer. If you currently have a throat damper in your chimney, which many homes do, it can still leak energy. A throat damper is an iron or steel frame with a plate that opens by pushing a handle or turning a knob. Throat dampers do not have a gasket, making it so the damper can never be 100% closed.
A lock top chimney damper has a gasket at the top of the chimney to ensure an air tight seal every time. Lock top chimney dampers also act as a rain cap, keeping rain and critters out of your chimney.