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Heating, Air Conditioning, Fridge, HVAC/installing duct blanket insulation on sheet metal duct


Greetings Fred,
I just finished installing a duct system in my parents new house using sheet metal duct for the main trunk and flexible duct for branches. About to start insulating the trunk for which I have purchased owens corning softr fiberglass insulation it is an 8.3 R rating and is 3" thick. The bottom of a good part of the trunk is 20" wide, do I need to use stick pins on that section of the duct to avoid sagging of the insulation?

Thank You in advance for any and all information in regards to this!



Any duct 18" or wider must have the pins. Note that I prefer weld pins to adhesive pins, which cal detach. The average installed thickness must be at least 2-1/4" to achieve R( "Installed Value"; just follow the directions as to "stretch out" and you'll be fine. Do staple the loints before taping. BTW: I prefer UL181 tape to FSK, which can detach.


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Fred Weldin


I can't help you if your whatsis won't work, people (Especially if it's a refrigerator); I have no experience with appliances, and I haven't been involved with H&AC service and repair since March 08, 1996 (Thank the Lord); I always send a "standard" reply to appliance questions and H&AC "Service and Repair" questions (about 20 a month), so if you want to know why your whatsis isn't working like it used to, ask someone else. A lot of my answers arenít read by the questioners; in that event, I always send reminders to read the answers for a month or more (the word "idiots" comes to mind - actually there's another more appropriate word, but discretion prevents its use here). If you have questions about how big a unit you need, if one room's warmer than the others, if you want an opinion oas to scope of work on bids received, etc. just ask. Do visit, there's a lot of good information on sizing, ductwork, efficiency, as well as some techniques accomplished DIY-ers can use to troubleshoot and improve their H&AC. Finally, I want to thank all of the kind, serious people whom I meet here: I enjoy working with you. My wife says I'm "snarky" from time to time; as for you others, please use your imagination as to the responses swirling on the snarky side of my brain when I read your questions.


53 years in the business. See


B of ME U of D 1965, numerous classes, seminars and a lot of "Hands On" learning since.

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