Square ducts are air ducts used in ventilation, heating and air conditioning systems in residential, commercial and industrial buildings. Unlike round ducts (circular or spiroducts), square ducts have a square or rectangular shape, allowing them to fit into tighter or more angular spaces.

Square ducts are typically fabricated from sheets of metal, such as galvanized steel, stainless steel, or aluminum, that are bent and joined into square or rectangular shapes. They can also be made of other materials, such as fiberglass, plastic, or flexible metal.

One of the main benefits of square ducts is their ability to transport large volumes of air. This makes them ideal for commercial and industrial buildings where a large amount of air conditioning or heating is needed.

Also, square ducts are easier to install in tight spaces or with sharp corners, which can be a challenge for round ducts.

Another advantage of square ducts is that their flat shape makes them easier to insulate and seal, helping to reduce energy losses. Specific fan boxes and diffusers can also be used to fit square ducts, allowing them to provide a larger amount of air conditioning or heating more efficiently.

In summary, square ducts are a practical alternative to circular or spiroducts in ventilation, heating and air conditioning systems. Their flat shape and ability to carry large volumes of air make them ideal for commercial and industrial buildings. Additionally, their ability to fit into tighter or angular spaces and their ease of installation and sealing make them a popular choice for residential buildings as well.