What do I need to know about air ducts & their materials for me to make a informed decision about ch[Here is the original question since I can't edit the question/subject that was cut off without warning:] What do I need to know about air ducts & their materials for me to make a informed decision about choosing a contractor for possible duct replacement?Some background: I am buying a 25 year old home that has entirely flexible ducting, most of which has lost its first or second layers based on the assessment & pictures from a home inspector as well as an HVAC contractor. Also, there is one duct line that is significantly bent or crumpled. So duct replacement was recommended by the contractor and they claimed that the inside of flexible ducting cannot be "cleaned". Is that true?December 29 2011 - Phoenix0YesReport a ProblemProblemSelect oneOffensive contentIrrelevant contentSpam (pure self-promotion)OtherDetailsYour emailPlease enter a valid email address.Submit CancelContent flaggedWe will review this content. Thanks for helping make the site more useful to everyone. To learn more, read Zillow's Good Neighbor Policy.We're sorry. This service is temporarily unavailable. Please come back later and try again.