Question Duct Insulation

karl Posted By karl, Aug 26, 2008 at 11:37 PM

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  1. karl

    karl
    Minister of Fire

    Apr 9, 2007
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    I just exchanged the heat exchanger on my new to me gas furnace, and while I was at the store, I asked about insulation the duct work.

    They have two types of insulation. A foil backed bubble wrap, and a paper backed fiberglass. One guy said the bubble wrap had twice the r-value, the other guy there said they had the same r-value. They both said the bubble wrap stuff is better, because you don't itch while installing it. It costs 176.00 for a 4' by 100' foot roll. The fiberglass is about 40 dollars cheaper. I'm looking probably three rolls.

    Which one is better to use? How much of a heating difference can I expect? The current ductwork runs through an unheated basement and an unheateed crawl space.

    Are there any better alternatives?

    Thanks

    Karl
     
  2. smokinj

    smokinj
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    Aug 11, 2008
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    on a gas furance i would go with the cheaper one,i used both on my wood furance it gest hotter so you need the foil to with stand the heat
     
  3. smokinj

    smokinj
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    Aug 11, 2008
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    and the other on my gas furance that doesent get as hot
     
  4. karl

    karl
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    Apr 9, 2007
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    Loc:
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    I was surfing around the reflectix website and saw a link for r-17.

    They say if you use this bubble wrap stuff on floor joist in the crawl space you get r-17. I find it hard to believe. Tell me what you think about it.

    http://www.reflectixinc.com/basepage.asp?pageIndex=541
     
  5. karl

    karl
    Minister of Fire

    Apr 9, 2007
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    Loc:
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    That's what I thought. I understand they're creating a dead air space but I still find it hard to believe. I know 6 1/4 of fiberglass bat will give you r-19, so maybe 10" of dead airspace will give you r-17. Here's what they say about the testing. I think I'll email them for a copy of it.

    Tests are performed to current American Society of Testing and Materials (ASTM) standards when a standard exists. For a copy of an actual test report, please e-mail us at customerservice@reflectixinc.com or call at 800-879-3645.
     
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