Energy is released from different processes into environment everyday across the globe. With the augmentation of the population it isnοΏ½t realistic to expect the energy demand to decrease, therefore currently available energy should be used more efficiently .In that sense, latent heat storage (LHS) has been popularized in last few decades because it can improve energy savings of thermal energy systems. The present paper contributes in showing the effects on system of including phase change materials(PCM) in a thermal energy system. System analyzed here is hot water tank for domestic use purposes. Analysis of system has been done using simulation program TRNSYS. Results come in a form of graphs that show charging and discharging times, quantities of energy stored, and temperature profile of watertank