Abstract: A venting system using natural convection cooling is disclosed in which a sleeve is inserted within a flue pipe. The annulus between that sleeve and the flue pipe is sealed at an inside end and the flue pipe is provided with a plurality of vent holes in the periphery of its outer end, which is positioned outside a building. That annulus forms a cooling passage and outside air is drawn through the annulus by a natural convection process to dramatically lower the flue pipe temperature. The outer end of that sleeve is open to a vent hood. An outer wall sleeve is also positioned around the flue pipe and sealed at one end in order to form an annulus containing an insulating air layer. That reduces the heat conduction to the outer wall sleeve, substantially reducing the outer wall sleeve temperature. The venting system also includes a vent hood having a double hood in which the outermost hood is spaced from the inner one.