Gas industry as one of the greatest sectors of energy, has a major role in environmental issues. A category of energy intensive parts in gas industry is heaters in City Gate Stations which consume colossal volumes of the purified gases. Different optimization strategies to improve the efficiency of these heaters entailing preheating, waste heat recovery of exhausts, insulating pipelines and mounting economizers or recuperators or even using renewable energy sources have been already introduced. Besides, finding the optimized geometry is very essential in improving the efficiency. In this study, a far efficient model for heaters was introduced using the thermal modeling of the process. Based on the properties of the inlet gas, the volume of the gas passing from the CGS and ambient conditions, the consumption of the fuel as well as heater efficiency have been computed as a function of inlet gas properties, CGS’s gas flow rate and ambient condition. Then, results were verified by real data taken from Arak CGS station in Iran. The comparison proves the great correlation between the theoretical and experimental results. Findings show that with an increase in the heater length, a reduction in thermal re-sistance coincides with a higher thermal hysteresis. This causes higher fuel consumption and lower efficiency. Moreover, the higher the length of the fire tube, the more heat is transferred to the pure water and the higher is the efficiency. Considering the optimized heater configu-ration the efficiency improves two folds; changing from 32% to 71%.