When setting up an air duct system, consider the sizes of the air handling unit and the condenser relative to the size of the room or building, as well as how airtight the room is. Another important factor is the type of duct work that is most appropriate for the area.
The sizes of the air handling unit and of the condenser are important in order to ensure sufficient airflow throughout the room or building. Both the floor size and the height of the ceilings must be taken into account when taking measurements.
The area must not have air leaks caused by damage or poorly fitting windows. An airtight room is important because air must be tightly enclosed before it can be controlled and exchanged.
The starting size also has to match the air handling system. The most commonly chosen duct size for home use is 20 square inches, which provide 400 square inches of air movement throughout the house.
The three main types of duct work are sheet metal, duct board and flexible ducts. While metal ducts are the traditional choice, they are not insulated and lose heat in open areas such as attics and ceilings. Duct board is cheaper and does not suffer as much from heat loss.