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  1. #1
    Join Date
    Feb 2008
    Location
    Tennessee
    Posts
    91

    best way to seal duct system

    I hope that even though this is a DIY question ...."that anyone can do that has even half the ability", that this thread won't get canned and we HO's can get some good information from all the Pros here.

    I'm sure most of the HO's that come on this site are more than just the common person anyway.

    What's the best way to seal up the duct system?

    How can you tell you have everything sealed properly?

    I'm sure something as simple as this can make any sysytem work better at the least. Most of the common people like me own a home with a system that was installed by less than "preffered" installation "professionals".

    We need things to look for on solid duct systems and flex systems to help improvements.

  2. #2
    Join Date
    Jul 2005
    Posts
    5,571
    Mastic tape. For more energy saving tips you can vist

    http://www1.eere.energy.gov/consumer/tips/

  3. #3
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,287

    Duct Sealing

    Quote Originally Posted by printmanjackson View Post
    How can you tell you have everything sealed properly?
    http://www.energystar.gov/index.cfm?...rovement_ducts

    Testing:
    1. Duct blaster
    2. Blower door for house leakage

    1. http://www.southface.org/web/resourc...22blowdoor.pdf

    2. http://www.infiltec.com/inf-btst.htm
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  4. #4
    Join Date
    Jun 2005
    Location
    The Gray Northwest
    Posts
    661
    Quote Originally Posted by hvacrmedic View Post
    Mastic tape. For more energy saving tips you can vist

    http://www1.eere.energy.gov/consumer/tips/
    Hey Medic, pardon my ignorence, but what is mastic tape? I've used mastic and I've used tape, but have never seen the 2 in one product.

  5. #5
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    apply HVAC mastic = thick paste, available @ 'big box' stores -- to all seams & joints of ducts & plenums [ boxes ]
    somewhat messy -- Goop hand cleaner removes
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  6. #6
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,338
    Quote Originally Posted by cem-bsee View Post
    apply HVAC mastic = thick paste, available @ 'big box' stores -- to all seams & joints of ducts & plenums [ boxes ]
    somewhat messy -- Goop hand cleaner removes
    I prefer this over "mastic tape". If you're not bad with a paint brush, the mastic can actually look somewhat neat when applied.

    For the OP, possibly the most neglected component of duct sealing is where the register boots meet the building drywall. Especially if that boot is adjacent to an unconditioned, ventilated attic. You could effectively seal all other components of the duct system (supply and return plenums, wyes, 90's, 45's, etc.), but leave this gap unsealed and the stack effect of escaping air from the house into the attic is considerable...and costly.

  7. #7
    Join Date
    Feb 2008
    Location
    Tennessee
    Posts
    91
    >In a typical house, however, about 20 percent of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts.<

    wow! 20% is alot to loose!

    This is great information!
    here is the link to this site if anyone missed it
    http://www.energystar.gov/index.cfm?...rovement_ducts

  8. #8
    Join Date
    Jul 2005
    Posts
    5,571
    Quote Originally Posted by big johnson View Post
    Hey Medic, pardon my ignorence, but what is mastic tape? I've used mastic and I've used tape, but have never seen the 2 in one product.

    Shurtape AF-100 or SF-685
    http://www.shurtape.com/Portals/0/EU.../AF_100_EU.pdf
    http://www.shurtape.com/Default.aspx...6&ProductID=98

    Once you try it you'll never use paint-on mastic again.

  9. #9
    Join Date
    Jun 2005
    Location
    The Gray Northwest
    Posts
    661
    Quote Originally Posted by hvacrmedic View Post
    Shurtape AF-100 or SF-685
    http://www.shurtape.com/Portals/0/EU.../AF_100_EU.pdf
    http://www.shurtape.com/Default.aspx...6&ProductID=98

    Once you try it you'll never use paint-on mastic again.
    How does it work for sealing transitions on the inside of the duct with a sound barrier @ 140* supply air temp?

  10. #10
    Join Date
    Sep 2005
    Location
    Texas
    Posts
    2,793
    Quote Originally Posted by printmanjackson View Post
    >In a typical house, however, about 20 percent of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts.<

    wow! 20% is alot to loose!

    This is great information!
    here is the link to this site if anyone missed it
    http://www.energystar.gov/index.cfm?...rovement_ducts


    I think its closer to 30% on average for an unsealed duct system

  11. #11
    Join Date
    Jul 2005
    Posts
    5,571
    Quote Originally Posted by big johnson View Post
    How does it work for sealing transitions on the inside of the duct with a sound barrier @ 140* supply air temp?
    Even better when heated. You will NOT get this tape back off again after it's been heated to 140.

  12. #12
    Join Date
    Jun 2003
    Location
    Hell Hole Swamp
    Posts
    4,180
    AF-100 is not mastic tape

    Mastic tape works great on metal, wont stick to ductboard very long at all

  13. #13
    Join Date
    Mar 2005
    Location
    Near Philly
    Posts
    98
    What about Aeroseal:
    http://www.aeroseal.com/

    Does this work?
    Seems like it would really, really, really depend on the tech doing it.
    Anyone with experience where this was used?
    thanks,
    howard

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