Hi, I have a third story attic space that I'm converting into a bedroom. My gas furnace and A/C unit is in the basement of the house. I have run two ducts up to the third floor space. Heating the space isn't too bad. I have an electric baseboard installed plus with heat rising, etc., it stays pretty nice up there. Cooling in the summer is next to impossible. I need a window A/C unit to keep it comfortable. Heres my question. I know the value of a "return" to the units in the basement. The only place I could place one is in the floor of the space where it will meet up with the return from the 2nd floor. Should I put this return in? I notice that the rest of the house mostly has returns up high on the wall. Would a floor return simply return my cool air back to the basement in the summer? The option of a furnace/AC unit on the third floor is not an option at this point. THanks for any suggestions.