Thermal performance tests of heat pipes developed for space applications at a horizontal elevation are not usually performed in order to avoid any performance contribution due to puddle flow inside the heat pipe. Instead, an experimental approach described in this study utilizing a regression study to create fitted curve by using different maximum heat transport capacities corresponding to different evaporator elevations is used. Under the frame of this paper, firstly, a test set-up enabling the estimation of the maximum heat transport capacity of heat pipes is explained. After, the procedure embodies a regression study to create fitted curve by using different maximum heat transport capacities at different evaporator elevations is presented. In addition, the approach for the determination of the effective thermal conductivity of heat pipes, which is very critical parameter for thermal design of satellites, is explained. Finally, the method to find the effective pore radius needed to calculate the capillary pumping pressure of heat pipes is given.