In this study, shell-side fouling of the shell and tube heat exchanger (STHE) designed for a textile firm was examined. The economic baffle spacing was determined for clean and fouled conditions. The energy and pressure loss analysis was performed using Bell –Deleware method. To predict the fouling thickness (FT), a prototype tube bundle was installed in the chimney of the stenter machine to expose to the exhaust gases. The FT on tubes reached to about 0.5 mm within three months. Fuel saving (FS) due to recovered heat and fan power consumption (FPC) due to pressure drop were calculated by assuming that FT varies linearly with time. In the result of the cost analysis, it was seen that economic baffle spacing was affected by R value which is the ratio of unit cost of natural gas to that of electricity but the effect of fouling on the optimum baffle spacing was not significant. Fouling affected optimum baffle spacing when R is greater than 15. In this study optimum baffle spacing was determined as 1.16 m for both fouled and clean condition, because of that R is 3.52 in Turkey at the time of the study.