Heating, ventilation, and air conditioning (HVAC) systems rely on a network of metal ducts to distribute air throughout a building. These ducts consist of sheet metal channels that extend from a central furnace or air conditioner to each of the occupied rooms or living areas within the structure. Traditional ductwork featured a square or rectangular shape, which allows installers to maximize available space within a ceiling or wall cavity. Round ductwork presents an effective and efficient alternative to traditional rectangular ducts, and may be the most cost-effective option in a variety of building applications.
Round ductwork consists of round or cylindrical lengths of duct that can range from short sections to several feet or meters in length. It generally also includes the fittings and transition pieces required to install a complete system of round ductwork. This includes tee-transitions, elbows, and other joints where the ducts are required to travel around a corner or obstruction. It may also include dampers, vents, and outlets used along the ends of these ducts as they enter a room.
Many builders and HVAC installers rely on special charts that enable them to transfer between traditional rectangular ducts and round ductwork. These charts are provided by manufacturers and can often be found in textbooks and industry publications. Generally, a specific size of rectangular duct equates to a specific size of round ductwork in terms of airflow. By determining the required airflow to each space, installers can refer to these charts to help them choose the correct duct size. The airflow created by each duct size is a function of the material of the duct, air pressure within the system, and the speed at which the air leaves the central furnace or air conditioner.
Round ductwork offers a number of advantages over other types of duct designs. It is the most economical, as a round duct requires less material than a rectangular one to move the same volume of air. These ducts also allow for faster air flow with less friction, which means the overall heating or cooling system requires less power, and experiences less wear over time. Round ducts also offer a naturally high level of sound absorption, and may not require sound dampers like those used in rectangular ducts.
One of the potential drawbacks to using round ductwork is that these ducts require more space than rectangular units. They may be too large to fit in small ceiling spaces, particularly those found in busy commercial buildings. In some cases, it may be necessary to lower the ceiling height within a space to accommodate round ductwork.