Hello Sifus.. I need help.. my living room 471sqft and dining area 103 sqft.. no partition between living and dining area.. total area for both space around 574sqft.. should I get 1 unit 24k btu? or 2 unit 12k btu ac? 1 unit 18k btu for living room and 1 unit 12k for dining? any other option? which option save more electric?