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Property "SU/SD from Bottom" Shows CL= for a Flat Bottom Duct

JC_BL
Advocate

Property "SU/SD from Bottom" Shows CL= for a Flat Bottom Duct

JC_BL
Advocate
Advocate

I am trying to show a "FB" tag on flat-bottom transition duct.  I believe I should be able to do this using a custom tag to show the duct property "SU/SD from Bottom".  This works for showing BU (Bottom-Up) and BD (Bottom-Down), like BU1 3/4 or BD2".  But this doesn't work for flat-bottom.  It always shows CL= (Centerline).

 

The transition duct pieces are offset to one side.  They are not on-center.

 

According to Duct Settings (Manage --> MEP Settings --> Mechanical Settings), I see that the ducting settings are correct:

Setting "Flat On Bottom" has the value "FB".

Setting "Centerline" has the value "CL=".

 

I have tried this in both Revit 2021 and 2022 with a test drawing.  Both versions show the same thing (CL=) for flat-bottom transition duct.

 

I have also checked the orientation of the flat-bottom transition duct.  Their bottom parts are facing down toward the floor -- exactly the way they are supposed to be.  I double checked this by changing them from flat-bottom to bottom-down 2", and the tag correctly shows BD2".  This means the orientation of the transition duct is correct and the transition duct is not placed on its side.

 

Then, why "SU/SD from Bottom" shows "CL="?

 

Please let me know how to fix this.  If this cannot be fixed, please tell me what the alternatives are.  Thanks.

 

By the way, there is a technical article in Autodesk with Incident ID 184759 that said, “Offset tag SU/SD top parameter reporting incorrectly in Revit”.  Seem like someone had a very similar problem as what I am having (seeing CL= when it should have been FT or FB).  The article claims that Autodesk could not re-create the problem in Revit 2022 -- that is contrary to what I am experiencing.

 

JC_BL

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craigjonnson
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Collaborator
Accepted solution

This would only show up if your height is equal on the C1 and C2 connectors. It could be possible that the fitting is rotated 90° so the tag information is reading incorrectly, i.e. your width value is the same.

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JC_BL
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Advocate

Thanks for the explanation of what "Centerline" means.

 

I thought centerline means on-center.  That was a misunderstanding.

 

As what you have explained, centerline means the depth in the two air openings are the same.  This explains why the transition duct that I have been using for testing are shown with CL=.  Their depth in their two air openings are the same.  This makes sense now.

 

Thanks again.

 

JC_BL

 

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