Abstract: A chimney liner adaptor is provided to allow air to flow between the outside environment and an annular space in a lined chimney flue. The adaptor may allow an air cooling system to operate but prevents undesirable elements from entering the annular space. The liner adaptor may be disposed between the chimney cap and the top walls of the chimney system and around the chimney liner. The adaptor may include perforated material, such as an expanded metal mesh, a metal screen, stamped metal screen, rugged netting, or the like. The perforated material permits gas flow, provides structural support for other elements of the adaptor, and filters out undesirable objects from entering the chimney.

Abstract: A chimney cap and a method for making the same are described. The chimney cap is more consistently and uniformly manufactured, which permits nesting. This is accomplished by forming the cap from single piece of expanded metal to create a substantially square or rectangular cage where each side of the cage has an integral flange that is bent substantially perpendicular to its respective side. The substantially square or rectangular cage is stretched to form a shaped trapezoidal cage, with a top portion of each side of the cage having a longer span that a bottom of portion of each side.