We bought a house that does not have any cold air returns. Basically the furnace just sucks air from the utility room in the basement, obviously not a very good setup. We have a great room that dominates the majority of the upstairs including a living room, breakfast area and kitchen....no interior walls. There are also 2 bedrooms and a hallway. Right now we have no AC unit, but will be installing one either this year or next. Obviously I want to get the air returns setup so that we have a much more comfortable house. The bedrooms will not be a problem, I can use the walls as ducts to the basement, and since the room below them is unfinished right now, I can easily route a new main duct over to the furnance for those. We have a coat closet pretty close to directly above the furnace that I can put a cold air return duct into. Also, I have a straight shot in the basement that runs through under the middle of the great room where I can put an air return vent . The question is for the great room. Can I install the cold air returns in the ceiling, then put duct work in the attic from the vents over to the trunk in the closet? Are there any issues doing this? I have only seen air return vents in walls, never in a floor or ceiling, so is there a reason for this, or just that most houses have interior walls to put the vents in? Also, I would put cold air returns in the floor, one in front of the island opposite side of the kitchen in the living room and one near an exterior wall farthest away from the furnace, but on the same duct that the vent in front of the island would be on. In the summer I would shut off the floor vents and close the ceiling vents, and vice versa in the winter. Thoughts? Also, I tried to explain the best I can, if you have more questions feel free to ask.