Duct error message

[maritza482LW]

I keep trying to draw duct coming from the Roof top unit but every time I draw the return duct it gives me an error message and it turns the duct from rectangular duct (which is what I want) to a duct fitting. See image below... 

[RSomppi · Accepted solution]

If the duct is not the same size as the connector in the RTU, you will need a transition. If you are not allowing enough room for the transition, Revit doesn't understand.

You need to either draw the duct long enough to allow room for the transition in the routing preferences to fit or use the size of the connector on the RTU for your duct.