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  1. #1

    Is it worth it to Seal my Attic HVAC Boots

    I've searched the forum and it looks like I do not have insulated boots and when i went up to the attic today, i noticed the boot was cold to the touch and had a small draft coming from where the boot meets the Sheetrock of the ceiling.

    I was thinking of using great stuff and sealing around the boot. I will use a combination of doors and windows great stuff and the normal expanding great stuff.

    I also noticed a small hole in the diffuser box (I think that is what it is) and I will use great stuff to seal that. There is also a small amount of mold on some of the tape.


    Bottom line, is it worth the cost for 20+ boots to seal with great stuff. I have blown fiberglass insulation and I live in Southern Alabama and will probably only live in this house for another 2-4 years


    Thanks
    Nate

  2. #2
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,627
    Any air leaks are worth sealing and any duct work in a unconditioned space its best to insulate as you are paying to condition the air as for usin great stuff be careful it can go every where might try caulking first

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,907
    20 leaking boots can be a lot of air leakage. Sealing them can greatly increase your comfort, and reduce your cooling bill, along with your heating bill.
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  4. #4
    Join Date
    Aug 2011
    Posts
    568

    Hmm

    Quote Originally Posted by Nate5452 View Post
    I've searched the forum and it looks like I do not have insulated boots and when i went up to the attic today, i noticed the boot was cold to the touch and had a small draft coming from where the boot meets the Sheetrock of the ceiling.

    I was thinking of using great stuff and sealing around the boot. I will use a combination of doors and windows great stuff and the normal expanding great stuff.

    I also noticed a small hole in the diffuser box (I think that is what it is) and I will use great stuff to seal that. There is also a small amount of mold on some of the tape.


    Bottom line, is it worth the cost for 20+ boots to seal with great stuff. I have blown fiberglass insulation and I live in Southern Alabama and will probably only live in this house for another 2-4 years


    Thanks
    Nate
    yes

  5. #5
    Join Date
    Jul 2010
    Location
    dfw tx
    Posts
    102
    I just sealed mine from the inside with the silver tape. I think it helped with condensation I was having since warm air was coming in and hitting the cold register.

  6. #6
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,721
    Ditto what these guys say.

    Quote Originally Posted by catmanacman View Post
    Any air leaks are worth sealing and any duct work in a unconditioned space its best to insulate as you are paying to condition the air as for usin great stuff be careful it can go every where might try caulking first
    Yeah, duct mastic, 1" spackle trowel & a paint brush first.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  7. #7
    Join Date
    Nov 2008
    Location
    SW Florida
    Posts
    23
    I sealed my in ceiling vents buy removing the vent and calking. Although I didn't think that they all looked that bad my humidity dropped 6 for 7 percent. I also sealed all of the recepticles and switches. In the summer I see mostly 51% dropping to 49 or 50 at times. Being in southwest Florida near a lot of water that isn't bad at all.

  8. #8
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,324
    I would use water based mastic to seal all gaps and seams on the boots, including any gap between drywall and boot. Be sure the register grill is off and remains off until the mastic has thoroughly dried. Same would apply if you chose caulk or foam over mastic.

    After sealing all seams with mastic, buy some shiny mylar coated duct wrap and then wrap the attic side of each boot. Tape all seams created by the wrap with foil tape. Mastic the tape. I'd do that vs. spraying "Great Stuff" foam everywhere. The foam will give you some insulation but the mylar coating on duct wrap is a radiant barrier, which you need with ducts in an attic.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

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