7 i! h [) Z; W& |option 1: Two seperated furnances and seperated control " b4 |, V. P7 b% a (for big house > 3000 ft) t3 Q( c; J6 Y- C* t2 v
option 2: One furnance with Zone Control device 0 i+ S% Q8 y) \& u8 ?4 c (three zones or fours zone will be good) - total efficiency will be higher) Z7 ?4 N2 C8 s& t& e& n; m5 K
0 ?; I% U. O- |) L& u5 a8 {
Total cost is not big difference.