We Purchased A New Home--actually Built In 1936-- Adjacent To The House Is A Sunroom.... When One Visits The Basement One Can See The Crawlspace--above This Is The Sunroom. When I Was Inspecting The Ducts, I Noticed That One Of The Ducts Goes Into The Wall That Leads To The Crawlspace. The Metal Part Of The Duct Is Suspended Between The Floor Of The Sunroom And The Dirt--sandwich Like—juts Out From Interior Wall—the Duct Never Touches The Floor/dirt.

Someone Told Me It's A Return For Cold Air. If This Is True, Are We Not Breathing In The Crawlspace Air? Could This Have Been A Duct Leading To The Sunroom For Cool Air During The Warmer Months? And Never Fully Installed?

Where Are The Conventional Places That Return Air Ducts Are Placed In A Home?... Also, Should I Plug It Up? I Would Think Insects And Other Matter Could Live And Or Accumulate In The Duct, Thereby Getting Inside The House Via The Duct.

Thanks For The Help.