Can't draw duct downward

[jean.laliberte]

I am trying to draw a simple duct down from a rooftop AC into a building - supply side.  I am not connecting it to anything yet; I will tap off it after.  I am drawing it from an elevation view.  I can see the duct being drawn exactly as I want it, but I keep getting the following error:  No auto-route solution was found. 

I am able to draw the same type of duct down on the return side.  What am I doing wrong?  Why does is not work on the supply side?

I have tried with "Automatically connect" on and with it off.  Same results.

[julianjameson8403]

Have you checked that the view is parallel or perpendicular to the ducts. If the relationship between objects is slightly off, even by 0.001 of a degree, then this can cause problems. Have you tried drawing in setion rather than elevation?

Have you also checked that you are using the same duct types and that they are set up properly with suitable fittings for what you are trying to achieve? Sometimes if you have fittings too close together, this can cause problems, especially with concentric and eccentric reducers. If so remove the reducer before doin the riser and then add the reducer again afterwards.

[jean.laliberte]

No luck with Section view.

The view aligment is good, because I can draw down from the return end-point, but I can't from the supply end-point.

Any other ideas?

[joeself]

Can you right click on the connector at the RTU and pick draw duct?

[Jrobker]

You may also want to check the connector within the family.

It is possible that is it facing the wrong direction.

[embolisim]

How does the size of the duct you are trying to draw compare with the connector size?

i.e. is Revit trying to put in a very long transition that is longer that the straight duct.

Try zooming out & drawing the duct stupidly long - you can drag of trim it back to the right length after.

also try drawing it (the duct) not attached to anything, then align it in all relevant directions & drag the duct end onto the connector.

[jean.laliberte]

Yes, I can select Draw Duct.  This is how I am drawing the duct on the Return side on the same AC unit (one of the standard REVIT MEP AC Rooftop unit).  The connector in the family is the facing in the right direction.

I tried drawing the duct seperately and connecting it manually, no luck. 

One thing I do notice is that when I select draw duct on the return side, the duct size immediately (and visualy) adjust to fit the connector on the AC unit.  On the supply side, when I select Draw Duct from the connector, a duct appears, but if you zoom in, you can see that the size is slightly different than the supply opening.  Adjusting the size of the duct does not seem to make a difference????

I just don't understand why the duct automatically adjust on the Return connector, but not on the supply connector of the AC?

[tblack_pe]

You may need to cut the section very close to the RTU, in my case I had to cut it inside of the skin of the RTU so that I could grab on to the attachment point for the unit.  The other item (depending on which manufacturer you are using) is when they have multiple supplies and returns.  I found that if I did not place an end cap on each of the side openings it was very difficult to grab the down draft connection.  If there are two openings, you must apply the smallest cover first, because you cannot attach the small one after.

[HVAC-Novice]

it seems you have an RTU family. The best way to draw is to click on one of the RTU connections and then draw the duct. After you selected "duc"enter the new height at 10'below or so.

Every equipment should have the connectors (in/out for air, water etc. )

also always good to have a 3D view open besides your floor plan

[jmmiller.southlandind]

The issue might be that you are attempting to draw the duct in section view, which inverts the duct width/height and your routing can not make the necessary fitting to accommodate. I suspect your return duct connection is square so the flipping of the duct height and width have no affect on the routing and that is why it allows you to draw successfully in section view. Yet your supply might be rectangular, which would have it's width/height flipped when drawing in section view compared to modeling in a floor plan.