In the present work, heat transfer rate and also pressure drop in a shell and coiled tube heat exchanger were evaluated experimentally. The experiments were carried out by a helically coiled tube with diameter of 0.57 cm, coil diameter of 8.6 cm, and pitch of 2.4 cm which was placed in a cylindrical shell. The hot water was passed in the tube side and the cold water was flowed in the shell side. Experimental study is made over a range of Reynolds numbers from 10,000 to 31,000 in the tube side and 250 to 1000 in the shell side of the heat exchanger. Heat transfer coefficients were calculated using Wilson plot technique. Nusselt number (Nu) and friction factor (f) values were obtain for analyzing the heat transfer and pressure drop in the heat exchanger. Moreover, new classical power–law correlations were proposed for estimating the Nu in tube and shell side and also f in the tube side. Correlation constants are then obtained using genetic algorithm (GA) methods.