Improper Ductwork Approved?

What?? Some sheet metal apprentice couldn't figure out how to make the final transition, and just walked away?

If I understand this correctly, the school might have cause for legal action against the installer.

Oh boy; you could become an expert witness in a court case....

Some pix might be amusing.

This system would never work for heat, ventilation, or a/c if the return air is sealed.

Is this a new installation? If it is you will make a fine witness, if it is an older installation (and you're in the northern hemisphere) it seems like a unlikely time to complain of no heat if a sealed return is the problem. It's not uncommon for supply and returns to have caps on the ends, with round pipe connections on the top, bottom, and sides. Can you see all sides for the full length? If it is roof mounted, could there be an opening in the bottom? Any return air inside the building? Any airflow at the supply registers?

You say the ducts seem to swell with only one zone open, until the crossover opened. That sounds normal. The bypass allows the blower to run optimally when restricted to one zone. With a blocked return the supply ducts could not swell, but the return would likely make some popping noise as a vacuum was pulled on it.

I've seen incomplete installs before. The worst was a return air sucking air from the crawl space; the joist were panned but not blocked. For a year the people couldn't figure out why the air in the house was so foul.

Good luck and let us know how it turns out.

So... was the install permitted and inspected?

May be the unit is still under installation stage!!! Some photos would be a better choice to understand the system more clearly in order to comment on it.

I have specified having the opening for an RTU return duct "on top" of the duct for sound abatement purposes, when the return duct was exposed for instance above the 'stage' area of one of those cafetorium-type spaces in a school.

If this unit is installed over an occupied space and this idea potentially applies, but they have installed the duct tight to the deck, try reaching up on top and poke around to see if there is a framed-in opening with an expanded metal grille up on top.

Only other thing I can think of is "incomplete." Sounds like there should be a ducted return from each zone served, with the "bypass" used to keep the unit on its fan curve when the outside air damper is closed or at minimum.

Someone got paid and stopped working? Job's done when the paycheck arrives, right? Well...unless the contractor fired their foreman on the job and he walked off to let them fend for themselves as far as current status of the project; though that kind of situation should have triggered an aggressive inspection of everything on that job to ensure nothing was sabotaged and everything followed the Engineers design doc's.
Ah well.

Well I am glad people agree with me that something might be wrong.

When I told the property managers guy to look and see if he saw what I thought I saw he said, "don't you believe your lying eyes?"

Usually when I come up with something like this I just was not paying attention when I should have been, or missed something simple.

I will try to get pic's if I get invited back. I am a vendor to these people, they are property managers for the owners, and we are talking about a tenant space so I can't be stopping in.

Maybe there is a structural reason - this is in an addition, and none of this is stick- built - the building is the real deal with stones and bricks, I'd say 1930's. Its got a skyscraper smoke stack that is not being used any more too.