_8 m- B8 c% B' |: S ^2 c; |option 1: Two seperated furnances and seperated control , V. a$ {3 M! r& H# o8 N( z J (for big house > 3000 ft) & |' V, H& ]2 X* o$ Woption 2: One furnance with Zone Control device 1 g, L B3 G5 ~) g# ] (three zones or fours zone will be good) - total efficiency will be higher1 X) J# S/ E7 u5 E4 a# K
9 c" M+ Z: G1 _/ RTotal cost is not big difference.