flex duct installation guide
It costs more to do proper design and commissioning. There’s one caveat to your attic suggestion, however. so, I learned. “I also love Table A1-2 that shows how much doors need to be undercut as effective return air paths – it shows how ridiculous the concept can be.” That’s Hank’s sense of humor for you. I stumbled into ductwork repair/change out,by testing before and after ducts were sealed by hvac companies. David R.: Yeah, it’s amazing the kind of stuff that finds its way into ducts. One interesting bit of info that many installers need to understand is that flex ducts need to have the inner liner pulled tight. w.g.) These use a ratcheting mechanism to fully tighten the tie, and then cut it flush. as difficult to achieve as getting hvac companies to actually train their workers how to install ducts. Technical Support Installation Instructions. Installation Instructions A manufacturers printed instructions in accordance with the terms of their listing Heaping insulation over the ducts is fine in dry climates but can cause condensation on the duct insulation jacket in humid climates. Assemble the metal ducting like a zipper When assembling pipe, start at one end and work the seam together like a zipper. Chapter 4 is where the meat of the manual is, the installation details, and that's the part I'll talk about here. 2) If the ducts run through the attic DON’T HANG THEM They need to lay on the ceiling joist or bottom cord, streached out and insulation heaped over them. Failing to do so may cause air leakage. While the proper sealing of ductwork in unconditioned spaces is nearly universally recognized as important, it is rare that a flex system get’s installed properly in these other important areas. The only way to secure them consistently is to use a tensioning tool. There you have it. Another problem that I see frequently is bends that are too sharp. Even with pliers, you just can’t get it tight enough. System Replacement I salute you sir, I salute you sir, Over the years, I have seen remarkable things on construction sites…major load carrying wood beams cut nearly in half to accommodate ductwork and my favorite…the ductwork seems to be the easiest place to throw trash, construction waste and even concrete. You really should go read his article because Mr. Bean is one of the most knowledgeable HVAC guys around. Stan: Yeah, I think nylon zip ties do have a shorter life in hot attics. per 100 feet [Pa/m]. As with most minimum standards, they’re the least you should do. Data Collection Additions. Manual D Residential Duct Systems sets standards for flex duct design and installation. Roll back the plastic or foil jacket and the fiberglass lining approximately 8 to 12 inches from the inner core. SUBSCRIBE TO THE ENERGY VANGUARD BLOG AND NEWSLETTER! hanging flex with mininum sag with 3″ duct wrap is easier said than done. 10 Year Warranty Download. If you can put an equal size duct inside the turn as shown below, they say you’re OK. Another biggie that I see all the time is sagging ducts. By submitting this form, you are consenting to receive marketing emails from: Energy Vanguard, 1924 Clairmont Road, Atlanta, GA, 30033, http://energyvanguard.com. The supports need to be at the manufacturer’s recommended spacing, but no longer than 4 feet. Air Ducts & Connectors w/out fittings Download. For duct sizing, they refer you to ACCA’s Manual D, for example. 67 0 obj
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See the photo I recently shared on our Facebook page (facebook.com/energyvanguard). The “zip ties” you referred to work very well IF they are tightened behind the first rib of the duct (with mastic applied to the sheet metal connection). I should point out that the ADC lobbied heavily to keep this data out of the book, but in the end, the data was included as Appendix 17. Here’s a link for those who don’t own the book: Manual D Table A1-2: Minimum Door Cut For Return Air. some cases duct leakage & air flow were worse than before the work was done. Installation Tips & Tricks — To cut flexible duct, use a steak knife from your kitchen drawer to cut through the outside jacket, fiberglass insulation and inner plastic core.Then cut the wire with a pair of wire cutters. The official recommendation from the ADC is that flex ducts should sag no more than 1/2 inch per foot of length between supports. When I updated and reposted the article recently at Green Building Advisor, Jack Lagershausen, the executive director of the Air Diffusion Council, sent me a letter. Remember they really should have more insulation than the ceiling. This installation has dedicated exhaust ductwork, but as with a simplified system, the HRV/ERV dumps the fresh air into the main return duct of the forced-air system. For the installation of flex duct in retrofit and existing building situations, follow all best practices and precautions described for new construction. You should then add the first piece of ductwork, and screw it so that it fits tightly into the plenum. 6 in. always -2 people to run flex. If you really can’t bring yourself to buy those sheet metal elbows, at least follow the Air Diffusion Council standards. The Flexible Duct Performance and Installation Standard is to be used as a comprehensive document in evaluating, selecting, specifying and installing flexible duct in heating, air conditioning and ventilating systems. Authorities considering adoption and/or reference of this standard should review all federal, state, local and other For homeowners, builders and HVAC contractors who want a superior IAQ product, EverClean™ comes GREENGUARD Certified and features a Lifetime Warranty to … • Always stagger take-off ducts by 12" to maintain pressure. How to make connections Oh, and you slipped in “Mr. Last take-off run to be located 12" - 18" from end. Credit applications can easily be submitted by fax at 713-849-0753. �����Y�����_��d�k8s���ӹ7�D8W��>q��
����O{>�Xv��=Ⱥ���!���AK��&a���\����>�8����x��AT��_�®��JZ. The ADC standards say, “Keep bends greater than or equal to one (1) duct diameter bend radius.” The language is a bit clunky, but the diagram below shows what they mean. If it sags, as you see here, the friction is higher and the air flow is lower. • Flexible duct work must be stretched tightly for maximum air flow. Debbie: Good advice. A couple of years ago, I even wrote an article about whether or not flex duct should be banned. Flexible Duct Performance & In Install ducts extended to their fullest length without compression. 3. HVAC Duct Construction Standards Metal and Flexible • Third Edition iii FOREWORD This Third Edition of the SMACNA commercial metal and flexible duct construction standards is another in a long line dating from the 1950s. 90 0 obj
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HVAC Load Calculations Keep ducts big for low resistance by using illustrated duct take-offs. Over time, it sags or gets bent and inhibits precious airflow through your system. I’ve seen several in attics that have broken, due to the heat I assume, so I’m not a fan of them. The straps that hold up the flex duct need to be no less than 1.5 inch wide. In our retrofit work, we’d rather see a customer with a well design and installed duct system where flex is used appropriately, then have the homeowner keep a poorly designed and installed duct system because they can’t afford the cost to replace it with sheet metal. Do not install near hot equipment (e.g., … I also love Table A1-2 that shows how much doors need to be undercut as effective return air paths – it shows how ridiculous the concept can be.