A new framework for addressing the practical industrial heat exchanger network (HEN) synthesis problem is presented. The new framework is based on a new object oriented representation of the HEN synthesis that allow handling of models of different complexity. To handle the increased complexity of the resulting optimisation problem a Simulated Annealing algorithm is adapted similar to that of Dolan et al (1989,1990). The proposed framework is implemented as the software tool HEN Explorer that successfully is tested on problems of varying complexity.