Properties.Fluid.Temperature_Ph refers to derTemperature_derP_derh which is only applicable to fluid=5 (Oil Therminol VP1)

In my case (ITECH example heater_with_pump_ramp_direct) an error is issued during the simulation, even if the solver keeps running and successfully terminates the simulation.

The problem is that the derivative of Properties.Fluid.Temperature_Ph is set to derTemperature_derP_derh. However, this last function assert incorrect fluid number if fluid is not equal to 5.