In Fig. 4 shows the set up, the tested heat pipe was monitored and recorded by a thermocouple type the evaporator, adiabatic and condenser of thermosyphon equal tree section. Ten thermocouples were installed to data Yogokawa MV1000 data acquisition with ±0.7oC accuracy, it used with type-K thermocouple ±0.5oC accuracy (22 points attached). was used with type K thermocouples to the inlet and outlet of the heating jacket and cooling jacket, thermocouple were attached to the Thermosyphon a case modifying the inclination angle of evaporator and condenser sections 0 60 90o and data logger were recorded. These were three points on the condenser, three points on the evaporator and three points on the adiabatic section. For experiment procedure, it began after set on tested parameters already. Then, the hot bath and cold bath had been maintained at operation temperature steadily. When steady state is reached, the temperatures are recorded in 10 minutes of interval time by data acquisition. Those recorded values are used to calculate the thermal performance, is obtained by; [4]