Harry (and everyone else in that discussion), hate to post a Yo photo, but that set contains a great detail of the split AC system units we were discussing the other day:
https://www.chicagoarchitecture.org/2018...outh-loop-nema-towers-over-all/850_1923/
These are the evaporator/heat exchanger portion of the system, the copper pipes sticking out deliver and return the refrigerant. They lead up to the roof (or mech floor) where they are fed by a giant condenser.
I imagine the most important advantage of this system is actually space and carpentry. It barely takes up any square footage and doesn't require any sort of soffits which are time consuming extra carpentry and drywall work. But for a landlord eliminating that mechanical closet that's maybe 3X5' so 15 SF you can rent out, you get instant profit. 15 SF is $45-$60/mo in most buildings that use this system. For something like NEMA with 800 apartments that's $40-50,000/MO in savings you gain instantly by eliminating a 15 SF closet...