In this video, This Old House plumbing and heating contractor Richard Trethewey explains how to retrofit central air conditioning.
1 Air is drawn in through a single return duct.
2 The air is then pulled into the air handler mounted in the attic where it's cooled.
3 A main supply trunk of larger ducts connects to the air handler.
4 Cooled air passes from the supply trunk to small-diameter ducts throughout the attic.
5 Each small duct is attached to a round outlet that's cut into the ceiling of each room.
6 The outlets are placed in the corner of the ceiling to avoid blowing cool air directly onto people in the room.
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