This paper deals with incremental system identification of district heating systems to improve control performance. As long as various parameters, e.g. valve settings, are kept fixed, the dynamics of district heating systems can be approximated well by linear models; however, the dynamics change significantly when these parameters change. For this reason, we attempt to identify the system using linear parameter varying models. We demonstrate how the so-called "Hansen Scheme," for linear time-invariant systems, can be employed for incremental identification of linear parameter varying systems as well. The approach is tested on a laboratory setup emulating a district heating system, where local controllers regulate pumps connected to a common supply. Experiments show that crosscouplings in the system can indeed be identified in closed-loop operation.