I live in a two-story home and would like to add a heating and central air conditioning system to my second floor. The second floor of my home is 700 square feet. I was thinking about having a contractor install the air conditioning unit on the outside, run the refrigerant pipe up to the attic where a gas furnace will also be installed. The gas furnace will serve as the air handler for the both the hot and cool air. Duct work will be installed throughout attic’s edges. The duct work will run down into the second floor where forced air will be blown out.
My second floor consists of four bedrooms, a full bathroom and a hallway. If I am running both heating and air conditioning throughout the second floor, where is the best place to install the ducts in the second floor so that the hot and cool air is maximized?
I have heard different opinions. One person has said to install them in the ceilings. A second has said to install them along side the top portion of the walls. And a third one has said to run the duct work from the ceiling to the floor using two registers per room with dampers. The register on the top should be used for air conditioning since cool air is heavy and it falls. The bottom one is to be used for hot air because hot air rises. What is the best ductwork approach for my second floor?