This vignette typically involves a section through a two-story volume adjacent to a one story volume (at a different roof height).
My question is, what do you do when a duct crosses these two volumes shown in a 2nd level RCP, and there is NO vertical shaft/mechanical room to change the height of this duct between volumes?
The NCARB 4.0 and 3.1 vignettes both have a vertical shaft/mechanical room at this cross point.
My exam vignette did not.
Dorf indicates you should adjust the plenum for the duct to run horizontally across the two volumes in the passing solution, so I did this, but that meant increasing the plenum of one of the volumes by about 6', which in my case turned out to be wrong.
I was really methodical with this vignette, finished early and double checked thoroughly. I literally spent the last 10 minutes staring at this duct cross point because it didn't seem right, but I was following the logic that Dorf provided. It's frustrating because I passed all the multiple choice sections Level 1, and felt I was adequately prepared for this vignette.
Can anyone explain why this is wrong?