AutoCAD MEP provides several ways to select MEP objects by system, domain, or connected branch within an object's contextual ribbon, at General panelSelect System drop-down.
To select objects by group, domain, or connected branches
To select connected branches
Select an MEP object, such as a duct, pipe, or plumbing or schematic object.
From the contextual ribbon for the object, click General panelSelect System drop-down.
Make a selection from the appropriate sub-menu, as explained next:
If you want to...
Use...
select the objects in a particular system, such as an HVAC system
Select System .
select the objects in all systems
Select System Group .
select the objects in a domain, such as, in the Duct domain, duct segments, fittings, or flex duct
Select Domain .
select all components in a run, or a portion of the run
Select Connected Branches Find and proceed to the next step.
Press tab to cycle through the connection options.
When the desired branch is highlighted, press Enter.
AutoCAD MEP includes other ways to select objects in a drawing, such as:
Move the cursor over an object, and click it.
Click outside an object or group of objects, drag a bounding box around the desired objects, and click a second time to select all objects that are completely within the bounding box.
Use icons on the Properties palette:
Select Objects: To create a selection set with your pointing device, for example, by creating a window selection.
Quick Select: To create a selection set filtered by a specific property, such as lineweight.