Would appreciate opinions on system recommended for new 5200 sq ft home in Chicagoland area where system would get average to above average use... Builder included (3) Carrier 93% HVAC 10 SEER (2 first floor, 1 second floor) with motorized zoned-damper systems and separate controls for each system. Also is 10 SEER still being used? Can replacement parts be obtained? Thanks!!