The Edit Duct Node Elevation command is used to change the elevation of all of the ducts at an intersection.
To edit a duct node elevation, go to
Ribbon: DM HVAC->Ducts-> 
->Edit Duct Node Elevation
Pulldown Menu: DM HVAC->Duct Centerlines->Edit Duct Node Elevation
Edit Duct Node Elevation Dialog Box
New Elevation: The elevation to use for the selected duct node.
Enter the new elevation and press the OK button. You will be prompted to select the duct intersection for which the elevation will be changed.
Select duct or label:
All of the ducts at the intersection will be updated with the new elevation.
You will be prompted to select more ducts. Continue to select duct nodes to be set at the new elevation, or press ENTER to finish the command.