Start with the local property, not a generic BTU chart
Johannesburg’s scale means the building matters more than a generic city climate claim. A shaded apartment in Sandton, an older Randburg home and a west-facing townhouse in Roodepoort can demand very different capacities and installation routes.
Security estates and sectional-title buildings may control external-unit placement, while freestanding homes often provide more routing choices. Highveld thunderstorms also make sound electrical protection and a compliant circuit especially worth discussing.