1#feinet2001 . ^( N! S* r8 g5 j1 [+ v* j - e) @6 q/ u$ o. n( Voption 1: Two seperated furnances and seperated control* F; }# Y) Z, x% d4 i9 ~
(for big house > 3000 ft)* T a) @# A8 U0 Q
option 2: One furnance with Zone Control device 2 K$ c- ~( Y$ ` U1 ?+ W; q
(three zones or fours zone will be good) - total efficiency will be higher & o2 t! L y8 q, g( v9 Z / q/ {9 p: `8 ^! l7 \/ j4 _Total cost is not big difference.