There are mainly two methods to enhance the performance of heat exchanger namely active and passive. In this study the wire coil inserts having three different cross sections namely circular, triangular and square with three different pitches(10, 20, 30mm) with 2mm wire diameter were used. The performance is investigated under constant wall heat flux condition and laminar regime in the Reynolds number ranging from 500 to 2200. Here distilled water is used as working fluid. The Nusselt number enhancement for circular, triangular, and square is from 3.73 to 15.26%, 5.54 to 17.24% and 6.08 to 21.26% respectively. Result shows that square cross section spring with pitch 10mm shows better performance among all the springs.