Brian, actually not my job but my house. It's been a difficult process to go through. Trying to stay out of everyones way, but I do have an interest in the job being done right. The 90 degree have cocerned me. The house mechanicals were spec'ed by an engineer, but all the contractors want to change the plans. The first two pictures show air handlers in a third floor loft. The larger one services bedrooms beneath, and actually the small ducts in the second picture to the right are from that unit going over a beam(through the deck) The door will be framed for better access. The air handler in the ceiling is the one that concerns me. It's duct run go 180 degrees over the air handler to turn back 180 degrees the other direction. If that makes any sense to you. It appears the installer installs the duct and then figured out how the air handler will work.