4 }9 A1 a% Q( z$ ^7 B( Doption 1: Two seperated furnances and seperated control , [1 j4 L) K7 X& f# R (for big house > 3000 ft)- w$ _3 U5 F4 M! Y/ N @* ~
option 2: One furnance with Zone Control device 0 d3 R4 G. h# c" B/ y. `6 ], z$ S (three zones or fours zone will be good) - total efficiency will be higher : U; v$ l6 s5 O# {. N1 l2 o* ]7 m0 o/ |' U
Total cost is not big difference.