I forgot something in my last post:
For open-loop systems, you often would like to link the injection
temperature to the abstraction temperature by applying a constant or
time-varying temperature differential. As this is not possible in the
standard user interface of FEFLOW, DHI-WASY provides a module for the
FEFLOW programming interface IFM for this, called SimpleOpenLoop. If
you need this, just email to the FEFLOW support (support@...).

Peter