Break Duct

The Break Duct command will break a single duct centerline into two ducts.

To break a duct, go to
Ribbon: DM HVAC→Ducts→  Break Duct
Pulldown Menu: DM HVAC→Duct Centerlines→Break Duct

You will be prompted to specify the location of the break on the duct centerline.

Select duct at break point:

The centerline will be broken into two segments. Both segments will point in the same direction as the original centerline.