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Improve Pressure Loss Method for duct fittings in Revit

Improve Pressure Loss Method for duct fittings in Revit


1. In Loss Method of duct fittings Properties, for the options "Specific coefficient" and "Specific Loss", it works for elbow, transition fittings(two connector fittings), and currently its limitation for Tee/Tap or Cross. so we have to use ASHRAE Table for these fittings.


Please add the option to specify the Loss Method as User Defined and apply the value to the Pressure Drop parameter, like when specific a coefficient, input both Main and Branch coefficient in Properties.


2. Currently when working with ASHRAE Table for different sizes, often shows”No ASHRAE table is applicable to the selected object" or incorrect table in Loss Method Settings dialog box.


For example, reading the table ER5-3 from ASHRAE standard, the table is only valid when Ab/Ac=0.5. But in engineering design working with ASHRAE Table,when Ab/Ac ≠0.5, we also refer to the value in table ER5-3.  Ab/Ac=0.5 is a test environment in ASHRAE, should not be the necessary condition.

So please remove unnecessary conditions when looking for ASHRAE  tables in Revit.


The following link features the similar path I went through, it brought up the problem:



Some users expressed a bit of frustration in the link above, then a solution came out later in Revit 2017. The solution supposes to work by leading us to built-in ASHRAE mapping, and the case status changed to “Implemented”.



But the ASHRAE mapping in Revit follows a very very strange way, it tends to break easily and does not give any informative prompt about what went wrong.


This feature would actually make the duct fitting database in Revit useful!



Community Visitor

Agree, currently you can't even use Revit for static pressure calcs because it can never recognize the ASHRAE data base table. It is crazy Autodesk still hasn't fixed this duct fitting issue. Static pressure calculations are very time consuming, and fixing this issue would probably revolutionize how the next generation of engineers do static pressure calcs.

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