Flex Duct - Does this product ever change
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  1. #1
    Join Date
    Jan 2006
    Location
    Lilburn, Georgia
    Posts
    52

    Flex Duct - Does this product ever change

    My 1976 flex duct in the attic is showing signs of age - it's brittle and in some places caved in. I've read some of the threads on this site with regard to the economy of replacement and from what others have said I have come to realize replacement may require a lengthly payback period.

    We plan to stay in our house for twenty or more years. If we change the flex it should be now, not later. I am considering a long metal duct with flex running off of it but that will more than likely involve too much attic floor space to be useful and still leave enough room in the attic to walk around in.

    Going back to the question of replacing the flex, I am wondering if there have been any advances in this product. With energy conservation so very important has anyone produced a "super flex" - even at a much higher price or do the laws of physics apply and limit the benefits beyond the current price/performance design of the product?

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,584
    Your 1976 flex duct is R4.2.

    New flex comes in R6, and R8 insulation values.
    And the exterior membrane is made better.
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    How many times must one fix something before it is fixed?

  3. #3
    Join Date
    Dec 2006
    Location
    Northern VA
    Posts
    389
    I would also suggest insisting on the foil wrapped in the attic.

  4. #4
    Join Date
    Jan 2006
    Location
    Lilburn, Georgia
    Posts
    52
    Beenthere - thanks - yes - I should have thought of this jump in R value and that will make a difference.

    Ok - beyond that, are there any flex products that offer substantial improvements over other products? Are some exterior membranes better than others?

    This stuff if used everywhere - just thinking someone must have tried to manufacture a much better product at a higher price. Is this possible?

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,584
    As everetts said, the foil wrapped.
    Its a better radiant barrier for the duct.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    The flex with the gray colored outer jacket has not lasted well in hot attics.

    The silver loking ,mylar( i think),jacket has lasted over 30 years in hot attics.

  7. #7
    Join Date
    May 2007
    Location
    Naples, Fl
    Posts
    889
    I have no first hand knowledge regarding this product but we did have a sample; we just never did anything with it.

    http://www.superiorairducts.com/

  8. #8
    Join Date
    Jul 2008
    Location
    Rydal,Ga
    Posts
    84

    Conditioned Attic Pic

    Condition Your Attic.... Then duct leakage is a benifit !!!!

    Foam the roof, if you plan to stay in this home the 20 years!!!!

    ESPECIALLY here in GA, increase efficiently, decreased moisture healthier home.
    Attached Images Attached Images  
    Last edited by kenny mac; 07-08-2008 at 09:31 AM. Reason: add pic

  9. #9
    Join Date
    May 2007
    Location
    Naples, Fl
    Posts
    889
    Quote Originally Posted by kenny mac View Post
    Condition Your Attic.... Then duct leakage is a benifit !!!!

    Foam the roof, if you plan to stay in this home the 20 years!!!!

    ESPECIALLY here in GA, increase efficiently, decreased moisture healthier
    home.
    As more vendors come on line the foam insulation my become a more viable alternative. Retrofit by the correct company is mandatory.

  10. #10
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,271
    Quote Originally Posted by kenny mac View Post
    Condition Your Attic.... Then duct leakage is a benifit !!!!

    Foam the roof, if you plan to stay in this home the 20 years!!!!

    ESPECIALLY here in GA, increase efficiently, decreased moisture healthier home.
    That looks great. The pricing policy of this forum may/may not allow us to discuss how much it cost to do an attic roof deck like shown in the picture. I'm personally curious as to the cost of the foam vs. radiant barrier roof deck, and the performance comparison. I do realize radiant barrier would require the attic remaining non-conditioned (i.e. ventilated) whereas the foamed roof deck, along with blocking off soffit, ridge, and other venting, could make the attic become conditioned space, thereby rendering duct leakage less problematic, and excess heat gain to or loss from the ducts virtually a non-issue.

  11. #11
    Join Date
    Jul 2008
    Location
    Rydal,Ga
    Posts
    84

    Go to my Profile and E-Mail Me with.. ???

    Quote Originally Posted by shophound View Post
    That looks great. The pricing policy of this forum may/may not allow us to discuss how much it cost to do an attic roof deck like shown in the picture. I'm personally curious as to the cost of the foam vs. radiant barrier roof deck, and the performance comparison. I do realize radiant barrier would require the attic remaining non-conditioned (i.e. ventilated) whereas the foamed roof deck, along with blocking off soffit, ridge, and other venting, could make the attic become conditioned space, thereby rendering duct leakage less problematic, and excess heat gain to or loss from the ducts virtually a non-issue.
    Go to my Profile and E-Mail me and I will be glad to answer ???? and help you locate you an installer.... You gain 30% efficiency when the ducts and air handler is in condition space..... Now you add duct leakage>>>>>

    Don't think about cost, think about the investment,
    If it were $5,000 to Foam a Roof at 6% 30 years would increase your mortgage about $29 a Month
    Depending how many units or size of roof this would be a guaranteed wash but in reality it could double or triple that monthly investment.

  12. #12
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,271
    Quote Originally Posted by kenny mac View Post
    Go to my Profile and E-Mail me and I will be glad to answer ???? and help you locate you an installer.... You gain 30% efficiency when the ducts and air handler is in condition space..... Now you add duct leakage>>>>>

    Don't think about cost, think about the investment,
    If it were $5,000 to Foam a Roof at 6% 30 years would increase your mortgage about $29 a Month
    Depending how many units or size of roof this would be a guaranteed wash but in reality it could double or triple that monthly investment.
    Well, I don't have a mortgage and I do have radiant barrier, so the questions regarding foamed roof deck were more from general interest on my part...I do have a friend interested in this process, as he has an attic similar to the one in your earlier attached picture. I am also always interested in the various ways to improve thermal efficiency of a residential structure, as I may at some future point look into energy rating and HVAC consulting as a sideline operation. I am particularly interested in hard data, not sales hype, as the only way I can get enthusiastic about a product, strategy, or process is to actually measure (or read of measured) performance. Benefits only come from performance...if the latter is not there, neither will be the former.

  13. #13
    Join Date
    Jan 2008
    Posts
    78
    Kenny Mac,

    Does foaming the roof really do any good if you have gable vents?? especially since I have an exhaust fan in the vent. How much of a temp drop would you expect in the attic by adding the foam?

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