Abstract: A fireplace chimney cap includes a body having first and second apertures in fluid communication defining a first cavity therebetween. The first cavity is configured and disposed to receive combustion air through the first aperture, then through the second aperture for delivery to a fireplace combustion chamber. The body has third and fourth apertures in fluid communication defining a second cavity therebetween. The second cavity is configured and disposed to receive combustion gases from the fireplace combustion chamber through the third aperture, then through the fourth aperture for exhausting exterior of the body. The first and second cavities are fluidly separated from each other. The first and fourth apertures are configured and disposed to provide a pitot effect to more readily draw both combustion air into the first cavity and combustion gases into the second cavity in response to the first aperture disposed upwind and fourth aperture position disposed downwind.