A Dual Zone setup involves two indoor air handlers powered by one outdoor condenser. This is the most popular configuration in our Dual Zone collection. It is ideal for small apartments or two-bedroom homes. A great example is the Bravo Milano Series 2 Zone 18,000 BTU (9k+12k). This allows for zoning where you only heat or cool the part of the house you are currently using. It provides a significant upgrade in efficiency over window units.