We are in process of a remodel which will yield 2657 square feet. The original part of the house has 8ft ceilings (`625 sq ft) and the addition has 12ft ceilings. To run a single hvac system through the house would require a soffit across the main living area at the 8ft level. We don't like the esthetics of this and are considering two separate systems. We appreciate any advice on how to configure this. Ductless systems are not our preference.