Before solve, please set “Nodal Forces” to “yes” in Analysis settings –> Output controls (needed for case 1, 3 and 4). 1. If you need heat flow at the interface and you have a contact at this interface, you can simply drag this contact and drop on to the Solution to create a reaction probe which gives you the total heat. 2. If you have a boundary condition (temperature, convection or radiation) scoped to surfaces and you need heat flow at these surfaces, again, drag this boundary condition and drop on to the Solution to create a reaction probe which gives you total heat. 3. If it is neither case 1 or 2, you can simply insert a force reaction probe and change the scope method to “Geometry” and scope those surfaces to get the heat reaction. For 3rd method, if the face is an interface between two bodies connected to each other via Share Topology, the above suggested method will not work and will yield 0, as the contribution coming from both the bodies is opposite and will cancel out. In this case, please use the 4th method. 4. Create a new User Defined result and scope this face. Enter the Expression for the User Defined result as EHEAT. Once you evaluate the results, the total heat value is shown in addition to min and max.