The velocity profiles, temperature distributions, average Nusselt numbers near heating wall, and maximum velocities of a circulating flow were calculated numerically by fundamental equations under different operating conditions including changing the Grashof number (at low Gr range), the location and number of heating walls, and the temperature difference between heated and cooled walls. The number of circulating flows is one or two owing to the configurations of heated and cooled walls under the present operating condition. Generally, the circulating rate was very slow and the temperature distributions were similar to those of conduction alone. In the case of a heated top wall, a domain of cold temperature extended widely as the circulating flow rate was increased, and it could be seen that heat transfer was suppressed. To check these calculated results, the velocity profiles and temperature distributions in small enclosures were measured experimentally and observed by a tracer under the same operating conditions as those of theoretical analysis. The calculated results agreed closely with the experimental ones.