Fittings Pressure loss Calculations

[Anonymous]

Good Morning,

I'm trying to use revit to perform ductwork and, with time, pipework calculations.

I used to do it with Magicad but i'm testing revit as an alternative.

I'm having troubles with that and i'm not happy with the results.

When i check my fittings i realize that revit does not assing anything to some fittings or automatically assign to bends/elbows an absurd coefficient from ashrae tables. (IMAGE: Revit01)

When i try to change it to a more reasonable coefficient i can do it if i choose just one fitting but if i choose more revit cannot find a proper table. (IMAGE: Revit02)

It's not possible to predefine coeficients to the more typical situation in the project?

Can't we change the coef for all bends/elbows at once?

Whats the reason for revit not be able to assign any coefficient for some fittings?

[scott_dakin]

For calculations Revit can be somewhat unreliable, for much the same reasons you have given above.

If you have access to MagiCAD I would highly recommend you give up on calculations in Revit as MagiCAD does it a lot better.

The feeling you currently have in that you are not happy with the results or accuracy will never go away unless Autodesk completely overhaul the calculation engines with Revit. So far this is not on the cards, as far as I know.

[rafal.lewandowski · Accepted solution]

Hi @Anonymous!

Indeed, sometimes the coefficients assigned to elements are not appropriate. As @scott_dakin mentioned to have more control at the moment, a much better solution is MagiCAD. If you mark those elements that you know coefficients are the same, you can change the Loss Method from ASHRAE Table to Specific Coefficient and in properties and enter the desired value.