This fireplace flue design can vent a fireplace while keeping out the elements using a raisable mesh cage and seal at the top of the chimney. When closed it provides a better seal than traditional chimney flues and also protects the entire chimney stack interior from outside elements. When open the device allows for ample ventilation while keeping out pests and debris. Even though the seal and vent is located at the top, it still can be conveniently operated from inside the house just like traditional flues. It can also be easily installed in new or existing homes.

The original concept sketch details the various components and basic mechanics of the device. Arrows indicate one direction in which sub-assemblies move when driven by a user intending to open the vent.

This sub-assembly is operated via the wooden hand crank. This crankshaft drives the small spur gear, which then drives the large beveled gear in the opposite direction. The bevel portion then forces the main drive gear to rotate which is brazed to the main shaft.

The upper sub-assembly shows a transparent cutaway of the smoke hood which houses the adjustable cage. The bottom circular piece is threaded such that it raises the cage and cap when the shaft is rotated. Weighted flaps on the cap also allow for an emergency pressure release when sealed.

An explosion of the lower sub-assembly and middle brace details the standard hardware used and how they are easily installed.

An explosion of the upper sub-assembly details the components that make up the height adjustable cage and cap outside of the smoke hood. The smoke hood adapts the rectangular chimney structure and funnels the exhaust into the circular cage ventilation structure.

This cross-section application image illustrates the device installed in a chimney stack and fireplace.