Type U Heat Exchanger (APK) is a form of heat exchanger which functions to heat the working fluid which will be fed to the next heating circuit. Generally the heat energy source used is exhaust gas which still has a high temperature obtained from the previous heating system. The amount of heat flow rate given by hot gas to water in the pipe is able to provide hot water supply. Preheater construction planning is made in such a way using the LMTD approach and the effectiveness and integrated CFD simulation in Anys15.4, so that the performance of the tool can be known. The final modeling results provide the flow and temperature distribution that occur in the heat exchanger in the heat exchanger. The capitalization uses 3D steady flow by selecting standard K- as turbulence modeling and activating the energy equation. The input data that is entered into the application is the result of measurements and calculations carried out previously. Based on previous research, the effectiveness of the designed heat exchanger has an effectiveness of 34%. After changing the type of heat exchanger, the analysis and simulation show that the effectiveness of the heat exchanger increases to 39%.