Correct BTU and tonnage but low CFM
I am finishing a walk-out basement and have been getting HVAC quotes. I have learned that the furnace BTU and AC tonnage is more than enough for the first floor and basement combined, but the blower moter is a bit under-sized for the first floor without even considering the first floor. Both companies that have quoted me have suggested a new additional split system. After researching I understand that just boosting the RPM of the motor is problematic, but what about adding 1 or 2 in-line duct fans and use the existing equipment to handle both floors?
Other pertinent facts:
It’s a straight duct-board install with flex duct (centipede).
There are two systems – one for the second floor and one first floor. There is a large 2-story room and both thermostats are in this large space.
I will be spray-foaming the entire basement.
Location is Charlotte, NC metro area.