The beginning of bathing action lies in the prehistoric times and the bathing had an important role in the daily life in the Hellenistic period for the first time. Romans, who had been influenced by the bath techniques in the Hellenistic period, improved architecture and heating system technologies of the baths and made them an important part of their life. The Roman bath culture that spread in Anatolia was turned by the influence of Turks into the Turkish bath and still goes on today. Because of the fact that, investigations are not enough about heating system of Turkish bath, to the best of the author’ knowledge, thermal analysis’ studies have not been done, the plan and projects of the heating systems of the bath and thermal conditions of the bath have not been investigated; extensive researches become necessary. On the other hand, energy efficient solutions with consideration of the environmental impact should be developed for historic bath buildings which are allowed for a restoration process. The study has been concentrated on the documentation of the information about the heating systems of a Turkish bath, therefore the Alibey bath from the Ottoman period; is chosen to investigate the use of heating systems from past to present. The study focuses on the evaluation of the collected information about the Alibey bath in order to examine the relationship between traditional heating systems and under floor heating systems of the Alibey bath. In the study, thermal analysis of the Alibey bath and the energy efficiency of two different systems are determined for different operating conditions by using the ANSYS Fluent commercial code. In addition to this, field surveys are composed of freehand sketches for architectural details, temperature distributions and flow analyses of different sections of the structure are examined. As a result of this study, two heating systems, old and new, are compared thermally. In the heating system with hypocaust, the amount of fuel to be consumed is relatively higher than the floor heating system. Besides, the temperature distribution in the floor heating system is more homogeneous than the hypocaust system.