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Basement system

The main duct that comes out of the plenum is rectangular. Air is directed up into the living area.

Branch duct

Smaller sections of pipe that carry air from the main duct to individual rooms.

Ceiling system

The main duct that comes out of the plenum is round. Air is directed down into the living area.


Tool shaped like a pair of pliers, which is used to make corrugations in the end of a sheet metal duct to reduce its size. 

Forced air system

A system of heating or air-conditioning in which the air is forced through a chamber connected to distributing ducts.

Main duct

A large duct that comes directly out of the furnace or central air source or plenum. It is sometimes called a trunk duct.


HVAC system accumulation and distribution chamber for connection of ducts. 

Return duct

The central heating or cooling system contains a fan that gets its air supply through the return ducts. These ducts should ideally be installed in every room of the house.

Stack duct

A rectangular duct that is used between wall studs to vent supply and return duct runs.

Supply duct

The ductwork that carries air from the air handler to the rooms in the house.

Oval duct compared to round duct

Oval duct provides a more efficient alternative to rectangular duct in  application where round can't be used. It is manufactured with the same techniques used to make round duct. As a result, oval duct shares many of the performance characteristics of round duct.


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Tips on duct installation
Prior to installing, you should...
About airflow and branching
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