The best ductwork material for your home is the type that properly fits the purpose as well as the specific location where it’s installed. HVAC ducts are the circulatory system of your air-conditioning and heating components. The total length of ductwork incorporated in a typical single-family home in our area ranges from 100 to 300 linear feet.
Ducts routed through your home actually comprise two separate systems that, together, continuously circulate conditioned air:
Supply ductwork delivers cooled or heated air from the AC or furnace into each room in the house.
Return ducts remove air from rooms and convey it back to the air handler to be cooled or heated again.
Three types of duct material are common, depending on function and installation requirements.
Sheet metal ducts are the prime material for long, straight lengths of ductwork which should be sealed with mastic and covered with insulation providing a sealed system. The sheetmetal material is long-lasting, and internal surfaces are generally very smooth, reducing air friction and supporting maximum airflow. Dust and other airborne contaminants are also less likely to accumulate inside. While the central sheet metal supply duct is typically rectangular, branch ducts leading to individual rooms are often round.
Fiberboard ducts are made up of fiberglass strands impregnated with resin to form boards and is an insulated form of ductwork. These boards are fabricated to form square or rectangular ductwork material of any size, then quickly cut to any length to fit a specific installation. The ductwork is stapled, taped, and sealed with mastic to prevent air leakage. Fiberboard is generally less expensive than sheet metal and can be quieter. The internal surface of fiberboard tends to be rough, however, slightly reducing airflow and tending to accumulate dust and other particles.
Flex ducts — so named because they are flexible — accommodate spans that aren’t straight or consistent. Flex duct is used in to connect the registers delivering air to the rooms in your house to either the Sheet metal ducts or the fiberboard ducts above. The flex ducts have an inner core of spiral-shaped steel coil plastic sheething with insulation and an external plastic or foil exterior material. Downsides of flex ducts include excessive heat loss or heat gain — unless the duct is properly secured and sealed on both ends of the connection and based on the insulation value. Also, aging flex ducts can deteriorate faster when exposed to the elements or damaged by outside sources.
For more about the pros and cons of the various ductwork material types, talk to the pros at Powers Heating & Air.