As one of the "freaking control guys", this is a picture of my worst nightmare. This is why I check the damper travel before I run the fans. I had a close call early in my career, and quickly learned my lesson.
I had 4 Rooftop air handlers do this just from the shipping. Had to use 20 LBS of "goof screws" to put it back together. One wall completely fell over. Just from shipping. Now that was a quality product!
These were like that when they cut the plastic off before lifting them on the roof. So much for a shipping claim. But then again if every unit was like that it was not from shipping. They need to build the walls a little stronger. Maybe put a few gussets in there like I did. Just the gussets made one hell of a difference. However if the damper shuts on one and it has a 12 by 12 wall. And 1.5" that would be a few tons of force against the wall. Can't make them idiot proof.
10 years back when i was a tinner i was on the other end of a roof sealing duct, heard a scrapping jet noise, felt and heard a boom, ran around the duct in time to see , from 100 ft away, a unit the size of a school bus scream, jump up off its curb about 20" and land, it did that once more before before the entire building lost power and went to generators. This was a major hospital. Never seen anything like that, like an invisible crane picked it up and dropped it three times. I heard later that all dampers below the building had been closed and on start up the air had to go somewhere. One guy broke his arm when the unit jumped with him reaching into it. The job closed so fast the tinners were sent home and reassigned to a different jobsite.
On larger AHU's there are three dampers return air , outside air , exhaust air normal position for these dampers is return air open with outside air and exhaust air closed on a call for economizer or free cooling these dampers will modulate most are either 0-10 vdc or 4-20 ma and usually they would or could track each others position or be controlled individually based on mixed air setpoint temperature 50 deg. as for smoke dampers or fire dampers they are before unit return to unit and after unit suppy and controlled by life saftey system and are most likely 120 volt spring loaded close on power failure or fire condition alarm.
Arguing with your Boss is like wrestling with a pig in
After a while you realize that while you are getting
dirty, the pig is actually enjoying it.
It is not exactly cheating, I prefer to consider it
creative problem solving.
25 years ago we had Bob Hope , Steve Jobs , and Johnny Cash today we have no Hope no Jobs and no Cash !
I can fix broke but i can't fix stupid !