- E9 D3 v0 y2 w( h) ?: M! soption 1: Two seperated furnances and seperated control7 m; T' E( M3 q+ \; U2 D3 C
(for big house > 3000 ft)4 e7 N& w7 |* N2 [
option 2: One furnance with Zone Control device 5 a4 d/ I% l D
(three zones or fours zone will be good) - total efficiency will be higher # c& L" S6 R5 ~5 i5 G7 g! ^& Q- o2 c8 Z1 J
Total cost is not big difference.