Reduced Basis (RB) method has successfully been used in 2D to solve heat transfer parametrized problems. In this work, we present some 3D applications in the same field. We consider two problems, the steady Thermal Fin and the time dependent Graetz Flow, we compare two reduced order modelling techniques: RB and Proper Orthogonal Decomposition (POD), then we apply a combination of the two strategies in the time dependent case.