An air conditioner ductwork system begins at the air handler unit and ends at the individual room vents. While most people may think the system is nothing more than a series of tubes, there are actual several individual components that make up the overall design.
Vibration Isolators
Since the air handler itself can produce a great deal of vibration, if not dealt with properly, the vibrations can pass into the ductwork and create a substantial amount of noise that could be heard throughout the house. In order to reduce this vibration and eliminate the noise that may result from it, vibration isolators are attached to the ducts at the point where they connect to the air handler. Vibration isolators are simply rubberized fabric sections of tube that help dampen the vibration before it can pass through to the ductwork itself.
Take-Offs
A take-off is simply the point at which the main duct line branches off into smaller section leading to individual areas of the house. These sections may also be where rigid ducts are replaced with flexible ducts to allow great ease of placement. The take-off duct connects directly to the wall opening where the vent is placed and held in place with either a prong-like system or an adhesive method.
Duct Stacks
While most ductwork systems are primarily laid out horizontally, some vertical ducts may be needed as well. Vertical ducts are run within the walls of the home and referred to as stacks. Stacks are often rectangular in size, usually longer than wider due to the limited space within the wall.
Duct Heads and Boots
When a vertical stack must be run through a wall to connect two regular ducts, transition pieces must be used to fit the narrow vertical stacks to the larger main ductwork system. A stack head is the portion that connects the top of the stack to the main duct. A register head is another form of transition piece that connects the vertical stack at an angle into a wall mounted duct. At the base of the stack, a stack boot is used to transition the smaller stack into the larger duct.
While there are several other components of a complete ductwork systems, these are just a few of the more common elements found in residential duct designs.