Carefully move the merged model by positioning the mouse pointer on a selected junction and holding down the left mouse button and dragging it to the desired location on the Workspace. If you accidentally click somewhere off the selected items they will be come unselected and it may be more difficult to move the merged model into position. If this happens, simply reload the original model and start the merging process over again. Very large and complex models may be constructed by building smaller models and merging them together. The sub-menu allows you to choose what objects to select in the flow path.
Absolute tolerance measures the absolute change in a variable using the appropriate units.
Relative tolerance which measures a change in a variable with respect to the variable itself. If the flow rates, for example, vary significantly through out the system being analyzed, then a relative tolerance is better suited. Using Relaxation Relaxation limits the amount of change while the program is iterating on the solution. The lower the number the smaller the steps taken towards convergence. If you model seems to not be able to converge try setting the relaxation to 0.1 which will reduce the steps size so that the iteration algorithm will not step over the solution as much.