Experimental investigation has been carried out in a closed loop rectangular natural circulation facility having a single heated macro channel dimensioned and built based on concepts of similarity and scale down circuit similar to the primary loop of a Nuclear reactor. The study aims to observe and critically analyze the thermal hydraulic parameters (Temperature Variation, Heating Power rises) as it affects transfer of heat by the NC flow along its hydraulic circuit at predetermined inlet subcooled set and sustained at 40°C, 50°C, 60°C and 80°C by regulating the coolant flow rate in the secondary loop. Heating channel power varies between 7kW – 13kW to portray several conditions of the reactor power in response to temperature changes base on the inlet temperature as a way of sustaining single-Phase flow through the flow loop while suppressing instabilities in the fluid circulation. Real-time signals of thermal hydraulic responses are observed via a graphical interface for data acquisition when stable flow or self-sustained flow oscillations are achieved. Results were analyzed at the (1) inlet and outlet of heater, (2) along the heated section and (3) inlet and outlet of condenser (4) the entire Loop. Pressure drops and Flow rate with respect to Temperature Difference was also analyzed to contribute for the acquisition of important data of natural circulation phenomena to be used for the design of large scale (prototypical) NC facility.