Natural convection in water inside an enclosure between two concentric cylinders has been investigated experimentally during heating and cooling process. This is made by the flowing of water as heat transfer fluid through the inner tube of the test section. The temperature distribution of water filled in the enclosure is established during heating and cooling process. As the natural convection phenomenon majorly depends on the heat source and orientation of the test section, the effect of mass flow rate and inlet temperature of heat transfer fluid on temperature distribution and heat transfer rate is investigated, first. Afterward, the effect of inclination of the test section on the temperature distribution is also established. The test section is inclined at 45o, 75o and 90o with the horizontal. The results obtained with different angle oriented test section are compared with the horizontal test section. It is found, convection heat transfer is dominant in heating process while in cooling process conduction mode of heat transfer dominated over convection. It is also observed that during the heating process, heat transfer rate is higher for vertical test section as compared with the other inclinations.