Natural circulation loops are frequently applied in renewable and nuclear reactor cooling systems. However, there are certain problems associated with these systems such as instability, having a low mass flow rate and consequently a lower heat removal capacity. Hence, when it comes to engineers, they are bound to overcome these problems in a way or another, moreover, they require a more stable and organized design. The function of heat removal from the heat source is susceptible to many parameters. In the presented work, a non-linear stability analysis method is used to evaluate the stability and also to give a rise to thermodynamic performance, Entransy dissipation method is employed.The mentioned methods are applied for a rectangular single-phase natural circulation loop with different heater and cooler orientations. In the current work, the effects of various parameters such as loop diameter, cooler length and heater power are investigated on the Entransy dissipation and consequently on the heat removal ability of the different orientations loops; and subsequently, a comparison is carried out between them.