How to tag air terminals in Revit: diffusers, grilles, and registers, step by step

Every diffuser and grille on a ceiling plan needs a tag. The reader finds out which system it serves, what type it is, and how much air it moves. Revit places the tag, and the tag family decides what it says.

This guide covers the job in order. You load a tag, place it, make it show the right values, and then deal with a crowded ceiling. RayCAD is a Revit plugin that tags air terminals and the rest of an HVAC sheet. After each step, you'll see where it costs time and what RayCAD changes.

What do you need before you tag air terminals?

• A view that shows the terminals. A reflected ceiling plan or a floor plan, set so air terminals are visible.
• A loaded air terminal tag. Air terminals have their own tag category, called Air Terminal Tags. A duct tag does not cover them.
• Air terminal tags turned on in the view. Check the Annotation Categories tab in Visibility/Graphics (VG) and the view template.

How do you tag an air terminal in Revit?

1. Load an air terminal tag

1. Go to the Annotate tab and open the drop-down arrow on the Tag panel.
2. Choose Loaded Tags and Symbols.
3. Click Load and browse to an air terminal tag. The tags that ship with Revit sit in the Annotations folder of your Revit library, under Mechanical.
4. Check that the tag name now appears next to Air Terminal Tags, then click OK.

The last tag you load for a category becomes the default. Load your firm's tag last.

2. Tag one terminal with Tag by Category

1. Open the ceiling plan.
2. Go to Annotate, Tag, Tag by Category, or type TG.
3. Set the orientation, and turn the leader on or off, on the Properties palette or the Modify | Tag tab.
4. Click a diffuser. The tag appears.
5. Drag the tag to move it. Press Esc twice to leave the command.

A diffuser is a solid element, so put its tag beside it, not on it. Many offices keep the leader off when the tag has room and turn it on when it does not.

3. Tag every terminal at once with Tag All Not Tagged

1. Open the view. Select the terminals you want tagged, or select nothing to tag all of them.
2. Go to Annotate, Tag, Tag All.
3. In the Tag All Not Tagged dialog, choose All objects in current view or Only selected objects in current view.
4. Select Air Terminal Tags.
5. Set Leader, Leader Length, and Tag Orientation, then click OK.

This is a good fit for air terminals, because nearly every one needs a tag. It skips terminals that already have a tag, and it runs on the active view only.

How do you make the tag show the right values?

A common air terminal tag shows a type mark and an airflow. To change what yours shows:

1. Select a tag and click Edit Family.
2. Save a copy under a new name.
3. Select the label and click Edit Label.
4. Replace Mark with Type Mark if every tag shows the same letter, such as L, L, L. Mark is an instance parameter and Type Mark is a type parameter.
5. Add Flow if the tag should show airflow, and set its unit format.
6. Click Load into Project, and choose to overwrite the existing version if Revit asks.

How do you fix zero airflow on an air terminal tag?

Airflow on a terminal comes from the duct system connected to it. If the tag shows zero or a blank value:

1. Check that the terminal connects to a duct, and that the system has no disconnected pieces. Revit shows warnings for these.
2. If the terminal is a custom family, open it and check that the flow parameter links to the connector's flow.
3. Wait for Revit to finish calculating after a change.
4. Confirm that the tag label reads the Flow parameter and not a different one.
5. Install the latest Revit update. In the first release of Revit 2024, air terminal tags could show zero flow, and users report that updates fixed it.

How do you tag a rotated or linear slot diffuser?

A tag follows the view by default and stays horizontal. A rotated terminal is easier to read with a horizontal tag beside it. If your standard wants the tag to follow a long terminal, such as a linear slot diffuser, the tag family needs Rotate with component turned on. Edit the family, change the property, and load it back into the project.

What goes wrong with air terminal tags?

What else breaks when you tag air terminals by hand?

Missed terminals. One diffuser without a tag becomes a question on site. If RayCAD can't place a tag, it says so, gives the reason, and takes you to the terminal. See how that reduces RFIs.

Model changes. When a terminal moves, its tag stays where it was. RayCAD's Retag tool tags the selected terminals again with the settings you used.

How does RayCAD tag air terminals end to end?

You pick the views. RayCAD finds every diffuser, linear slot diffuser, and grille, decides where each tag goes, places it, and lists anything it could not place. You review the result. A click-saver plugin speeds up each manual click and leaves the deciding and placing with you.

RayCAD tries the sides of a terminal in turn, above, right, left, and below, and moves to the corners only when every side is full. It works in floor plans and section views, and you save the setup as a preset for the project.

What should you check before you issue the sheet?

• Every diffuser, grille, and register has a tag.
• Tag values match the air terminal schedule.
• No tag covers a light, a sprinkler, or another tag.
• Airflow values are not zero.
• Section views show the same terminals as the plan.

RayCAD supports Revit 2021 to 2027. Start a free trial, or get a demo and an onboarding call. The HVAC tagging page covers the ducts and equipment behind the terminals.