Pumping: Piping circuit
The pipes circuit produces friction head losses, which have to be kept at a reasonable value.
The "Hydraulic Circuit Definition" dialog asks for the choice of a Pipe type (including diameter), and a total piping length.
It allows inclusion of a number of elbows, as well as eventual other Friction Loss factors for diverse hydraulic singularities, valves, etc.
The overall friction head loss appears on the little graphical tool (below the green line), as a function of the flowrate. It should be kept negligible at nominal flowrates of the system, by choosing the appropriate pipe diameter.