Wind directional cowls (“Fireman” type) are constructed in a way that allows them to shift position in relation to wind direction. Even the smallest gust makes them rotate, which creates exhaust vacuum that sucks combustion gases out of the flue.
Stainless Steel Chimney Self Adjustable Cowl Duct Pipe Metal Spinner Pot Guard
Stainless Steel Chimney Self Adjustable Cowl Ventilation Duct Pipe Bird Guard
Round Chimney Cap Stainless Steel Chimney Pipe Cap Universal Chimney Cap
Stainless Steel Chimney Cowl with Clip Rain Protector Pipe Cover Chimney Pot Cap
13" x 13" Chimney Cap Stainless Steel Chimney Cover for Fireplace Vent Pipes