I am finishing my basement and have come to the heating portion of the project. The room is 25x17 there is a cold air return in the center of the room coming out of the ceiling. Should I move this to the floor or can I leave it be? And what size run and grille should I use? If I do move it can I place it on one end of the room or should it be in the center of the room? And second will two supplies be sufficient if I put one above each window? Any ideas would be greatly appreciated.