Polyester duct insulation over reflective bubble wrap?
Unfortunately my HVAC installer did not appropriately insulate two 10 foot steel ductwork trunks. The installer used two tightly wrapped layers of reflective bubble wrap…exactly as advised against here on GBA.
This is in a unconditioned attic so it’s a double thermal whammy. The installer did a nice job of taping everything so at least it looks nice.
I measured a peak of 118F in the unconditioned attic and noticed about an 8 degree difference in AC register temp on hot sunny days Vs cloudy warm days. Therefore I think there are significant gains to be made if I up the insulation on the ducts.
Space is tight in my attic and its difficult to maneuver around with exposed joist and low ceiling. I’m looking to up the insulation on the two trunks and the registers using something that is easy to install, not labor intensive, and preferably not fiberglass based.
So I’m considering covering the trunk and registers with 2 inch foil faced polyester insulation like this:
https://m.grainger.com/mobile/product/DUCTMATE-Duct-Insulation-38G227
It’s hideously expensive but i only need one roll and it seems like a good fit for my situation due to
-Decent R8 value.
-Not susceptible to condensation damage
-Easy to work with
-No fiberglass.
Do you guys see have recommendations or opinions on this plan of attack?
Mark
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Replies
Seems like a good plan. If the tape on the bubble-pack is reasonably well done it's fine to just leave it. You may want to peel it back in a couple of places to see if they mastic sealed (or at least HVAC taped) the joints and seams of the sheet metal.
If there's no mastic or aluminum tape over the joints & seams of the sheet metal you may have to strip the bubble pack to do the job right.
Thanks Dana. I’m learning so much here. I really don’t blame the HVAC installer as I think he might actually believe reflective bubble wrap is effective.
I must say this quip of yours regarding reflective bubble wrap (from 2013) cracked me up.
“....if you're installing your ducts on the outside of a space station, this is really the right stuff!”
https://www.greenbuildingadvisor.com/question/reflectix-still-claiming-r4-2-for-its-bubble-wrap-my-hvac-guy-is-hooked
Maybe I still have a shot at a career in comedy? :-)
I just scored a 4’ x 50’ x 2” roll of the Ductmate polyester on eBay. $210 delivered. Outer layer a little scuffed. That was a bargain in my opinion.