To insert diffusers on the drawing, go to
DM HVAC 
Diffusers Insert Diffusers
The Diffuser Information dialog box will appear. You will be inserting some S-1 diffusers; set the specifications to match those shown below. Press OK.
Design Master HVAC will take you to the drawing and will prompt you to specify the insertion point. Locate the diffuser in Conference 102 as shown below and specify the rotation angle of the diffuser. When you have indicated both an insertion point and rotation angle, Design Master HVAC will again prompt you for an insertion point, allowing you to insert another S-1 diffuser with the same specifications. Insert a second diffuser as shown below, indicating insertion point and rotation angle. When you have finished, press ENTER to complete the command.
Next, use the AutoCAD Copy command to copy the two diffusers already inserted in Conference 102 and place the two new copies at the other end of the room, as shown below.
Next, you will place supply diffusers in Offices 103, 105, and 107. To do this, go to
DM HVAC Diffusers Insert Diffusers
The Diffuser Information dialog box will appear. Set the specifications to match those shown below, then press OK.
Note that we purposely had you input a CFM that is not compatible with the definition of diffuser S-1. After pressing OK, Design Master HVAC will display the Warning dialog box shown below.
Press Change, which will return you to the Diffuser Information box. Select diffuser S-2 and press OK. Insert one diffuser each in Offices 103, 105, and 107 as shown below.
Next, use the process already described to insert return diffusers R-1 as shown below. In the Diffuser Information dialog box, select Callout R-1 and set the CFM to 400.
For this tutorial, we now wish to edit the return diffusers in the three offices and change their CFM.