And wallbangers are contained within the apartment... They are not placed outside on the ground and require running wiring and refrigerant lines up the outside of the building -- which is something only the owner of the building can do as that is outside of the boundaries of the "apartment"...
That issue is something the OP has never clarified as of yet... Does he own the "apartment" ? Does he have the legal right to install equipment located outside of the "apartment" or does he need permission/approval of someone else who controls/owns that area...