The induced Bow, due solely to buoyancy, through a vertical annulus, with a uniformly heated inner rod and an adiabatic shell is analysed for radius ratios r(2)* = 1.5, 2.0 and 2.4. Measurements with a 3.68 m tall annulus, inner rod radius 12.5 mm and r(2)* = 2.4 in ambient air indicate that the numerical predictions of annulus height, heated surface and fluid temperatures are too high, although the length average Nusselt number is well corroborated. Experimental heat flux range corresponds to Grashof number ranging from 2.6 x 10(3) to 8.5 x 10(4) and measured induced flow rate varied From approximately 850 to 3800 cm(3) s(-1).