On a recent trip up into my attic, I found out that the air conditioner was blowing cold air into the attic. In several places at the AC unit, the foil tape had become unsealed. In the interest of not cooling another room, I plan on re-taping it, but I have the following concerns: Does the tape failure indicate a possible failure/fault in the system that should be investigated? Is there any surface preparation that I need to do to make sure the tape stays stuck long-term? On the plus side, the people who did your ductwork made an attempt to seal it! On the minus side, they used tape instead of mastic. Tape can come off, as you've discovered. If you really want to do an A+ job, seal those joints with a generous application of mastic. It's basically a sort of putty-like substance intended for duct sealing. I just had a new furnace installed. They sealed the ducts with 3" aluminum backed mastic tape. It's expensive stuff, this roll costs $40 on Amazon. It might be cheaper your local HVAC dealer, and I doubt you will find it at Home Depot or Lowes.

Carlisle HVAC manufactures a few different mastic tapes, they have a tool to help find a local distributor. Here is a good read about sealing ducts and with mastic vs tape. A particularly interesting paragraph: One of mastic’s chief advantages is that, unlike some tapes, it performs well without clamping. Yet mastic will not prevent a joint from opening up. “Mastic is not a mechanical fastener — you still need sheet-metal screws, and scrap metal or fiberglass drywall mesh for big holes,” notes Davis. “You need to be sure that everything will hold together on its own merits. But, unlike with tapes, you don’t have to worry about whether the surfaces are clean.”Browse other questions tagged hvac taping or ask your own question.Paint & DIY Tapes Painting & Masking Tapes Clean Release® Painter's Tape General Purpose Masking Tape Heavy Traffic Carpet Tape Light Traffic Carpet Tape Heavy Duty Electrical Tape Drywall & Plumbing Repair

Fiberglass Drywall Joint Tape Paper Drywall Joint Tape Fiberglass Wall Repair Patch Aluminum Wall Repair Patch Auto & Reflective Tape Tread & Grip Tapes Fiberglass Duct Repair Tape This duct tape is a waterproof solution that bonds to both flexible and rigid materials. Metal Duct Repair Tape This waterproof solution bonds to both flexible and rigid materials, meeting the needs of the professional contractor and homeowner alike Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui.Donec sed odio dui. Sold by Avalanche Brands and Fulfilled by Amazon. Do it yourself and save. Our annual DIY Event features top brands with easy-to-install products for your home. Frost King AC43H Air Conditioner Weatherseal Tape, 2-1/4 by 2-1/4 by 42-InchDetailsM-D Building Products 2006 Air Conditioning Weatherstrip, 1-1/4-by-1-1/4-by-42 Inches, Gray Duck Brand 1286294 Air Conditioner Foam Insulating Panels, 18-Inch x 9-Inch x 7/8-Inch Each, Pack of…

2.2 x 8 x 14.5 inches 2.4 ounces (View shipping rates and policies) #95,077 in Home and Kitchen (See Top 100 in Home and Kitchen)how to install air conditioner wall unit #40 in Home Improvement > Building Supplies > HVAC > Weatherproofing > Weather Strippinghow many watts does a ac unit use See all 8 customer reviewsac unit for rv See all 8 customer reviews (newest first) well made, does what it is supposed to to. not all products to that now a days. It's not tape it's just a strip of foam. Not what I thought I was buying this is the best stuff for installation of in window air conditioner! Fine for my use! See and discover other items: window tape sealing 1-7/8 in. x 35 yds. 1-7/8 in. x 12 yds.

Tough and Wide Gorilla Tape 2-7/8 in. x 50 yd. Extreme Weather HVAC Foil Tape 2.83 in. x 50 yd. 394 Extra Wide General Purpose Duct Tape in SilverScotch Tough Extreme Hold Duct Tape 1-7/8 in. x 120.3 yd. 555 FlexFix UL Listed Tape 1.89 in. x 10.9 yd. Waterproofing Repair Tape 1-7/8 in. x 60 yd. 398 All-Weather HVAC Duct Tape in Black Scotch 1.88 in. x 25 yds. Tough No Residue Painter's Duct Tape (Case of 12)Wide Duct Tape, Indoor Silver General Purpose (60-Yds)Foam weatherstripping and rope caulk are easily removed and will not damage your window. Most window air conditioners have an expanding curtain on either side to help seal any gaps between the window frame and the air conditioner, but sometimes this seal isn’t perfect. Even extremely small gaps can leak air, which reduces the efficiency of your air conditioner and may let bugs and dust into your home. There are several ways to seal these gaps, but the simplest method is to use adhesive-backed open-cell foam weatherstripping to fill the space and prevent air leakage.

Smaller gaps can also be filled with a claylike material called rope caulk. Clean the surface of the window and air conditioner around the gaps. Remove dirt, grease and dust to ensure proper adhesion of the weatherstripping. Measure the length of the first gap. Cut a piece of adhesive-backed foam weatherstipping to this length. Peel the paper backing off the cut strip of weatherstripping and position the seal, sticky side up, along the underside of the window frame. Press the strip along the window frame to get a smooth, tight seal. Do not adhere the weatherstripping so that it rests in front of the gap. This will not seal it properly. The foam must be within the gap so that it expands to give an airtight seal. Measure the length of gaps that are 1/8 inch thick or smaller. Tear off a length of rope caulk to match. Rope caulk is similar to putty or modeling clay but is removable at the end of the cooling season when you remove your air conditioner. Press the caulk into the gap. If the gap is deep, you may need to press two pieces into the gap to fill it completely.