1#feinet2001 8 d1 F3 e" S4 N$ m6 \% Q# Z/ i, z- e
option 1: Two seperated furnances and seperated control % t5 G; ~4 D; s" O) D (for big house > 3000 ft)1 i" r6 f/ p% {3 P* ?
option 2: One furnance with Zone Control device 0 {! L3 j9 z z2 _2 O) U (three zones or fours zone will be good) - total efficiency will be higher 9 g! u! P9 I" c, f0 ^1 r3 y% T x$ @1 g3 K
Total cost is not big difference.