The sheet metal company installed the ductwork and roof curb correctly. Then the rooftop HVAC unit was placed on the roof curb. The electrical power and thermostat were properly connected and the gas line was properly connected. The sheet metal company called a separate HVAC contractor who did a “start-up” on the unit. Finally the system was ready for balancing. We arrived on site only to find that there was no airflow into the ductwork and there was a lot of noise coming from the ceiling area below the HVAC unit. The video shows what we found.
I’ve actually come across this situation several times. It can happen to the most reputable contractors. Part of the reason this sheet metal company, and others, hire us to test and balance their systems is to make sure these “oversights” get caught before the building is turned over to the owner.