Revit forces branch to have certain direction

[Siberian]

Imagine a plan view of a piece of horizontal pipe drawn "sideways" on the screen. I am able to insert a 45° branch so that it points up to the right. If however I attempt the same thing - only to the other side so that the branch would point down to right - Revit will force the branch to be placed the opposite way - pointing down to the left. The pipe has no slope, so I don't understand why Revit would have an "opinion" about the branchs' direction. And why does it accept it in the first instance? The branch has has a symbol which will switch its direction once placed, but as soon as I attempt a pipe run from the branch, Revit immediately switches it back. Any idea why this happens??

[tzframpton]

Revit's pipe/duct is ran backwards from what our minds think. For instance, from supply diffuser back to the supply discharge of a unit will set the direction of flow from the unit to the diffuser. Clear as mud? A return would be from the inlet of the unit to the return grille. This puts the flow in the proper direction.

 

I still model from the unit out to the grilles for ductwork. Also, for piping/plumbing, I run it from the source (say a floor drain back to the sanitary connection for the site, or from the domestic water source out to the fixtures). So I deal with it, always have and I guess always will.

 

-TZ