This media is in the public domain (free of copyright restrictions). You can copy, modify, and distribute this work without contacting the Smithsonian. For more information, visit the Smithsonian's ...

Before selecting duct materials, it helps to understand how air flows from your heating/cooling unit through the duct network. Most systems use either a hot air furnace or an air conditioner ...

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the ...