SetParameterByName makes change in Dynamo but not Revit

I am attempting to set the value of the ‘Specified Exhaust Airflow’ on a Space. The default value is 0.00 CFM. I have a list of spaces and a list of CFM values of equal length that I am assigning. If I check the output from the spaces coming out of the SetParameterByName node in Dynamo using GetParameterValueByName it appears to be working, but in Revit nothing appears to be changing. Any ideas as to why this may be?


Guessing that it might have something to do with the mechanical units conversion/confusion issue.
Not sure what it might be though.
Wild guess…
30 millimeter per minute = 0.0010594400015927045 = 0.00 cubic feet per minute

Hi Jared,

Dynamo uses ft3/s, 1 ft3/min = 0.016667 ft3/s. If your looking to set the values you need to convert your values before you assign them as shown below. Good Luck!


For more information about parameters have a look at the REVIT API lookup Table.

That is good advice, but doesn’t Dynamo use the RVT’s unit settings, not Revit internal units?

Compiled Revit Lookup at and

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Thanks for all the advice. It was indeed a units issue. Why Dynamo uses ft3/s is a mystery to me, but as long as I’m aware of that I can work with it.

Does Dynamo use all of the current RVT’s unit settings, or just length (mm, inch, foot, etc.)?

I believe it only handles length, area & volume conversions at the moment:

[quote=“Dimitar_Venkov, post:8, topic:4221”]
I believe it only handles length, area & volume conversions at the moment:
[/quote]That’s good to know.