I sometimes get my software packages confused - in my class at AU, I made the comment that you could change the rise drop symbols in Revit MEP...and I was gloriously wrong. I've done in in ACAD MEP, since it's a block, but there's isn't a family or profile anywhere you can edit to change these...so I had to spend a little time figuring out how I would make this work for me.
Revit MEP comes with a variety of different rise drop symbols as their defaults - so they've got most of the range covered:
I created a detail family that includes a solid fill, and add model lines around the edges so it could be aligned with the geometry in the rise drop symbol. It's not going to update if the duct size changes, but by the time you get to CD's to produce the documents, hopefully you'll know what the duct size will be. This is kind of similar to the pipe cut symbol we found earlier this year - it's not part of the model, and it's manual, but you can use this to get the results you want.
Keep in mind that in order for a rise drop symbol to appear, the duct has to cross to a higher level. Just stopping it doesn't produce the right symbol...so I'm working on a union that has the fill symbol nested in the family. It sort of works, but just like the one I directly use, it doesn't change size if the duct size changes.
Let me know if you want the annotation, and I'll email it to you.
Mmmm....humble pie....tastes a little funky, but when you earn it, you gotta eat it...
thanks - David B.