What type of air ducts are most common in AC systems?

Flexible ducting is the most common type of air ducts used in air conditioning systems due to its versatility and ease of installation. It can easily navigate around obstacles, making it suitable for various configurations needed within buildings. This type of ducting is often made from a core of wire and surrounded by insulation, which helps reduce energy loss and maintain the temperature of the air being delivered. Additionally, the flexibility allows for quick adjustments during installation or maintenance, accommodating different layouts without requiring extensive modifications.

Other duct materials like Schedule 40 and Schedule 80 PVC piping are typically used for plumbing and drainage systems rather than for air distribution in HVAC applications. While they are strong and durable, they lack the necessary flexibility and insulating properties required for effective air circulation and temperature maintenance in HVAC systems. The mention of ABYC P-76 rated ducts refers to specific marine standards that may not apply broadly to residential or commercial air conditioning systems. Thus, flexible ducting stands out as the most practical and efficient choice for HVAC installations.