Our neighbors put in a "dual" system where the furnace and AC modulate up and down rather than just going on and off. Dampers can direct where the airflow goes to maintain even temperature through the different zones. They really like it because those differences go away. The HVAC guy who just left is going to quote it to us, but it requires a new AC condenser, new furnace, new evaporator coils, and new thermostats. Our unit is over 20 years old, so will be due for replacement sometime soon. But all I see for that "dual" conversion project is...
