The Duct layout preference dialog box lets you define layout preferences for a duct run. You can also select terminal duct connections types. Duct layout preferences are stored with the drawing. You can use different layout drawings and share layout preferences between drawings.
In the HVAC workspace, use any of these methods to access duct layout preferences:
- Click Manage tab
Preferences panel Duct 
- In the Properties palette Advanced Routing Options click
(Preferences).