1#feinet20019 Z, q, ^( O% q/ h4 t& H8 T
5 v2 n! x6 | n( C4 ]
option 1: Two seperated furnances and seperated control7 b2 V7 w* U) [& J% Y( Z
(for big house > 3000 ft)" J8 b# [1 X n
option 2: One furnance with Zone Control device ' G; X. Z+ v7 n/ Y
(three zones or fours zone will be good) - total efficiency will be higher , U1 y6 ~8 {; K5 H# v6 U1 C8 r& J6 n, k( O
Total cost is not big difference.