Creating Supply, Return, and Exhaust Duct Systems

When you select an air terminal or piece of mechanical equipment that is not assigned to a system, you can:

• Draw duct to connect the components. If the duct is assigned to a system, the air terminals and mechanical equipment connected to it are added to the same system.
• Manually create a system using commands on the Create System panel on the ribbon. The type of component selected determines which type of system you can create. For example, when you select a return diffuser, Revit assumes you are creating a duct system. When you select a heat pump, Revit lets you choose between a creating a duct, power, or piping system.

1. Select one or more of the air terminals in a mechanical plan view.
2. Click the Modify tabCreate Systems Duct.
3. In the Create Duct System dialog, specify the following:
   • System Type: the type of air terminal selected in the view determines which System Type it can be assigned to. For a duct system, the default system types are Supply Air, Return Air, and Exhaust Air. If you select a supply air terminal, the System Type is automatically set to Supply Air.
   Note: You can also create custom System Types to handle other types of components and systems.
   • System Name: uniquely identifies the system. Revit suggests a System Name or you can enter a name.
4. Click OK.

   The previously unassigned system is moved to the Mechanical folder in the System Browser.

5. Click Select Equipment, and select the mechanical equipment for the system.
   Note: If more than one connection is available for the selected mechanical equipment, in the Select Connector dialog, select a connector, and click OK.
6. Click Generate Layout or Generate Placeholder.

   The Generate Layout tab is activated.

7. On the Options Bar, click Settings to open the Duct Conversion Settings Dialog where you can specify the offsets and duct/flex duct types for the Main and Branch segments, and the maximum flex duct lengths for Branch segments of the ductwork.
8. Verify that Solutions is selected on the Generate Layout tab.
9. On the Options Bar, select a Solution Type from the drop-down list: Network, Perimeter, or Intersection.
10. If you selected Perimeter for Solution Type, you can specify a value for Inset.

    The Inset value determines the offset from the bounding box surrounding the components selected for the system. You can specify a positive or negative value to place the perimeter within or outside of the bounding box, respectively.

    See Generate Layout for information about potential routing solutions.

11. Click or to cycle through the proposed routing solutions, and select one that best fits the plan.
12. If necessary, click Modify, and reposition duct segments.
13. Click Finish Layout.

    The ductwork is created for the system.

    Repeat this procedure, as necessary, to create supply, return, and exhaust duct systems, using the System Browser to verify that all components are assigned to a system.