When changing the air flow of the air terminal in the properties, an error message of "Enter a value or formula starting with "="" appears in Revit.

[sburtonJAMXV]

As mentioned above, when changing the air flow of the air terminal in the properties, an error message of "Enter a value or formula starting with "="" appears. Does not matter which family is used. Asked around and another person in the office has experienced the same problem starting this week.

Found a get-around, which is to tag the air terminal, then through the tag (Delayed double-click) modify the air flow. Anyone know of a proper solution?

[iainsavage · Accepted solution]

https://forums.autodesk.com/t5/revit-mep-forum/quot-enter-a-value-or-a-formula-starting-with-quot-qu...

[handjonathan]

Hi @sburtonJAMXV 

Thanks a lot for posting your question to the forums!   Has the solution suggested by @iainsavage helped with your issue?
 
We look forward to hearing back from you with more information so we can help you as a community! 

[sburtonJAMXV]

It appears that updating Revit to the newest version (Revit 2024.3.1 Update) does resolve the issue. For those who can't update right away use the workaround I mentioned in the first message or use the "Modify | Air Terminals Flow: 0 CFM" bar at the top of the screen. (Though your Flow Parameter needs to be set = ###_Flow Parameter).

Thanks for the help @iainsavage.

[jdeyoung]

this is happening to every family I have,  Somehow Mechanical-Flow has been added to every mechanical equipment and duct accessory family I have ever created and makes the family un-editable.

[iainsavage]

That sounds as though someone has added a Project Parameter in your project or template and then associated it with those categories.

Or maybe they've used a utility like DiRoots Paramanager to add a parameter en masse to every family in certain categories.

I don't think Autodesk parameter names would be hyphenated so I think this is a custom parameter.