% N6 X1 ^+ I! s7 w# e6 ~option 1: Two seperated furnances and seperated control ! I. `! C, j* U8 T1 S( ` (for big house > 3000 ft) ) l3 p5 Q$ O& J, P$ P; j+ y9 Woption 2: One furnance with Zone Control device 5 O0 G* N) J. L0 y; P5 L; ~
(three zones or fours zone will be good) - total efficiency will be higher% j" e/ `! B2 G* |+ d5 a# u! }
6 x+ L0 T" [3 K) d4 C2 oTotal cost is not big difference.