This paper presents a model of counterflow shell and tube type heat exchanger in which water was working as heat transfer interacting fluid. To perform thermal analysis of shell and tube type heat exchanger we were first decided to design a heat exchanger. This was capable of cooling water from 55 oC to 45 oC using water at room temperature (25 oC). The designing was completed according to the Kern’s method as well as to suit the norms of tubular exchanger manufacturer’s association (TEMA). After thermal model design calculation our purpose was to ensure the correctness in design. Heat exchanger was designed on CAD software and its thermal analysis tested on ABAQUS 6.13. It was also fabricated based on the data obtained from mathematical modelling and tested under actual loading conditions. Altered materials were used for heat exchanger components during its thermal analysis. All these observations along with their discussions have been discussed in detail inside the paper.