Heating, ventilating, and air conditioning a building is, in a forced air system, accomplished using ductwork. Ducts are a series of sectioned conduits, or tubes, which convey either heated or cooled air from the furnace or air conditioner, throughout the building. These ducts, along with the actual furnace and air conditioning unit, are ordinarily thought of as the building’s heating, ventilation and air conditioning (HVAC) system. Hard pipe, used to transfer water or gas, is not considered ductwork.

The piping or tubing commonly used for ductwork may be manufactured from tin, or sheet metal, fiberglass, or flexible plastic. A type of flexible ductwork may be manufactured from vinyl-encased insulation, through which a coiled wire is inserted. This flexible ductwork is popular due to its ease of installation, and its insulating properties.

Because of its importance in the overall utility, and livability of a particular structure, ducts are often among the first items to consider when designing a new building, or when purchasing an existing structure. Attention to HVAC systems, ensuring constant and efficient performance, is vital to proper building maintenance. A common problem with air ducts is that any contaminants in the air flow will be concentrated by the ductwork, and disbursed throughout the building. Frequent duct cleaning is essential to reduce this occurrence.