You typically name duct system definition for the duct system for which it will be used, such as supply or return air. Systems help maintain consistency throughout a run and across multiple drawings in a project. When you change a segment’s system, all components having valid connections to that segment are updated to the new system.
Duct system definitions specify duct size calculation parameters and duct display information, such as layer key settings, rise and drop display style, and display properties. The settings for a system definition control many of the display properties of a duct system You can assign a layer key style to a system definition to dictate its layer, color, and linetype. You can also configure a system definition for duct size calculations.
You can assign a system definition to a system group. Duct runs with different system definitions cannot connect to each other without changing the system for the connecting duct run. You can, however, assign a system group to different system definitions. This allows duct runs from different system definitions to connect while maintaining the same system for each run. For example, you can assign the same system group to Supply - High Pressure and Supply - Medium Pressure. You can then connect duct runs between these 2 systems while maintaining their original system definitions.
The default templates include many duct system definitions, such as chilled water, heating hot water, and steam. Duct system definitions are stored with a drawing. You can use different system definitions for different drawings, and you can share system definitions among drawings.