Separate hydronic piping networks into loops to calculate the flow and pressure loss for each loop.
To add hydraulic separation

Hydraulic Separation panel
(Add Separation).

Graphics panel
When a tap is used, the exact point of separation is located between the tap and the main or header. When a tee is used, the exact point of separation is between the tee and the branch pipe or any fitting connected to the tee. The common pipe, the pipe between the secondary supply and return junctions on the header, displays a flow of zero.
The read-only parameter, Loop Boundary, indicates whether the selected pipe is a boundary for separated loop.
To remove hydraulic separation
Hydraulic Separation panel
(Remove Separation).