Revit MEP- Editing Air Terminal Family for more Versatility

There is a common problem with the Revit MEP Air Terminal Family. When we place an Air Terminal, we want to be able to align it to the edge of a ceiling grid. The problem is, that when we use the align tool to align the terminal to the grid, there is no reference line on the edge of the air terminal to align to. See reflected ceiling illustration below.

With this months AEC Article, I am assuming that you are an MEP Engineer who recently started using Revit and you have a linked Revit Architectural Model that you will be adding your MEP systems to.

What we want to do here is edit this air terminal family so that there are reference lines on all sides of the air terminal. Once we do this, it will allow us to use the Align tool to align the air terminals to the ceiling grids without having to use the Move tool.

Our first step is to edit the air terminal family. Inside the family editor, you should see something like this:

On the project browser on the left, double-click on: Views all > Floor Plans > Ref. Level, to go to the floor plan view of the terminal. You should see the floor plan like this:

The next thing we need to do is create some reference lines. These reference lines are going to allow us to align the edge of the terminal to the ceiling grid.

1. Draw reference lines on each outer side of the air terminal like this (I am showing the reference lines in bold red dashed for clarity).

2. Draw a dimension going from the left reference line to the right reference line. When dimensioning, make sure that you are selecting the actual reference line and not the other symbolic line or mass element. Use the TAB key to cycle through the selections until you hit the reference line. If you do not dimension from reference line to reference line, these reference lines will not be parametric when you resize the air terminal.

3. Once you have the dimension, make another dimension that goes from the Left reference line, to the center reference plane, to the right reference line. See Illustration below.

4. Click the 1-0 dimension and click the EQ. symbol so that you have this:

5. Click the 2-0 dimension and change the label to Width.

You should have this:

Repeat steps 2-5. You should end up with this:

The dimensions should be going from reference line to reference line, as explained in step 2. Again, use the TAB key to cycle through the selection.

If you did the above correctly, you can click on Family types on the left and change the width to 2-6 and click Apply, your reference lines will move with the sides of the air terminal. Change the width to 2-0 again and click apply so it is correct.

Finally, click finish sketch on the left side of the screen and click the button on the left.  You may get a dialogue box like this:

Go ahead and click Yes.

4. Now. For the final test, use the align tool to align an air terminal to the ceiling grid.

As you can see, I have just aligned the edge of my air terminal with my ceiling grid. If you later decide to create a new family type and resize the air terminal, your reference lines should automatically resize with the air terminal geometry.

This page last edited on Thursday, June 03, 2010