forced warm-air system

In this type of system, air is heated in a furnace and blown by a fan through a network of ducts to the rooms of a dwelling.

air return

Duct directing air from a room back to the furnace to be reheated.

furnace

Device creating heat and blowing the air through the duct system.

plenum

Joining duct between the furnace and the hot-air distribution system.

elbow

Connection or part of a duct for altering the direction of the hot air.

wall stack section

Vertical duct carrying hot air upward toward the registers on the upper floors.

damper

Mechanism for regulating the volume of air passing through a duct.

main duct

Duct that leaves the furnace and carries hot air toward the branch ducts.

branch duct

Duct, usually made of sheet metal, carrying the hot air toward the registers.

hot-air register

Adjustable grill located at the end of a duct through which hot air is distributed throughout a room.