1#feinet2001 : v( s1 r% W. _% z' E $ k8 w0 @) L' F. Toption 1: Two seperated furnances and seperated control* S5 P) z' }; D, g; u
(for big house > 3000 ft)6 G+ h$ `* k$ n" h, F
option 2: One furnance with Zone Control device , j8 Q7 v' k- J% O: H$ u/ E (three zones or fours zone will be good) - total efficiency will be higher2 J2 I% L) C" L
9 _& y* H% j& y' ^9 w! {. R
Total cost is not big difference.