Well my question is basically two fold.
1. I am finishing my basement and adding registers and a return air to the system. I see that the ductwork currently has dampers in the system. I am drywalling the ceiling and curious why dampers are needed? Can't the airflow be adjusted at the registers in each room? Help me understand.
Dampers allows for a system's airflow to be accurately balanced. If it's done at the registers, it makes more noise when not completely open. A damper will too but because it's deeper inside the system, dampened by sheet rock and insulation, it's less noticeable at the register.