I also don't think many really realize the difference in quality between the larger AHU versus the packaged rooftop unit.
The packaged rooftop...
Has thin sheet metal, virtually no insulation, fan sections running 1:1 or worse, condensing coils held together at the end with tie wraps(in some cases) that allow them to be split and cleaned however this causes much stress over time. The economizers are generally not very good... general quality I'd describe as worst in the industry for equipment because of the attempt to make them cheap and smaller. However, for @25% more cost you can get a higher quality packaged unit, however it still suffers from the coil issues and the overworked fan design and lack of insulation.
Each RTU has literally hundreds of components so if you have 25 on your roof constantly you have something going on wrong.
I suppose also every low-price-leader contractor can slam in packaged rooftops. An actual decent system requires a mechanical. Maybe this is another contributing factor.
