Unico Flexible ductwork longevity

MikeT_Swampeast_MO

My Unico is fine about 10 years after installation and 5 after operation. Mains are commercial, leak-proof spiral wound with one-piece fittings. Branches are mainly central vacuum tubing--perfect fit for their connectors and what Unico recommended to me for a "best quality" job. Only the last 3' or so is Unico flex (required for noise control). I insulated everything with bubble foil glued on with contact cement on both surfaces. The laundry/utility room still doesn't have a finished ceiling in part because the Unico hangs in the ceiling there and my initial design for service access proved wishful thinking for someone my size with multiple fused vertebrae in his neck The ducts for that room are all flex because they're so close to the mains and there's no sign of deterioration.

clutterbug

Hi thanks everyone for your comments and help. An update on my situation is that I had an independent HVAC contractor here and verified that my install is perfect and by the book, and that he has never seen Unico tubing do what mine did. I have read everyone’s comments and thoughts and considering that the tubing in the entire house has failed, Not sure how this could be an insulation or moisture problem in the attic. The tubing in the unfinished basement spaces disintegrated the tubing in the various insulated attic areas disintegrated. I really think at this point I have to take my case up with Unico. And here’s the kicker. The evidence of failure comes only when you touch the tubing. In other words it’s just barely holding together and when you touch it it falls apart. Perhaps it’s not a logical conclusion but it would lead me to think that perhaps there are other folks who have a Unico system and are not aware that their tubing is disintegrating, because after all who goes around examining their duct work until you’re trying to change your upgrade something. OK now I’ll sit back and brace myself for everyone’s comments please be kind to me 🙂

clammy

Just wondering did your unit have a freeze stat mounted on the suction line by your air handler ,has any one started your unit to ensure that the refrigeration end is charged and running properly and not freezing the coil .just a thought the coil could be freezing up ,freeze stat shuts condenser off ,fan continues to run coil slowly thaws releasing all the moisture into the duct work until the freeze stat makes when the coils defrosts and the process goes on and on .on another note we all wish everything would last forever including over and our loved ones life but if you look around now everything has a warranty and life span who would thought the 20 years ago copper lines sets would have a limited warranty 10 years well read the next pre insulated line set muller wolverine who ever 10 years and how about standard foil flex ?i m sorry but I kinda don’t believe that it a manafactures issue I believe it may have some thing else that contributed to the deteration .i have only seen some thing similar on foil insulation that got soaked from a leak and over a short time the outside jacket desinerated .it s been awhile since I ve installed a unico but I never remember the sound attentuning tube not being fragile and fall apart when handled .i hope you get to the bottom of your issue . Peace and good luck clammy

Kybeans403

The company that I work for has been Installing Unico/Spacepak systems for 20+ years. I have see a handful of issues like this. In my opinion this issue could be caused by a few things.
1- inadequate insulation
2- poor taping/sealing of outer jacket (vapor barrier)
3- massive temperature difference from uninsulated or poorly vented attic. (R8 may not be enough)

I've also seen sound attenuation tubing actually wet like a sponge which would certainly cause disintegrating material.

We also have been replacing 15-20 year old systems where the duct system still looks brand new. Unicos due to their nature hold water in drain pans until fan shuts off, so increased unit pitch is key, those blowers can and do pull moisture from the pan, through the evap and into the duct system. Proper static pressure and duct design as well. Unico wants 1.5 " wc. @ 24" PAST THE RESTRICTOR PLATE. If you don't have proper amount of outlets and supply plenum you will never get to that number.

clutterbug

Thanks for that comment. Going to show it to my installer. Especially the part about unit pitch and poor taping and sealing. I will say that the tape is pulling off in a lot of places.
This project has hit a stall as we wait for various trades to finish their part of the project. So this is a good time to re-examine the taping job. Thank you for chiming in!

mikeg2015

Unico has a very specific procedure for taping the duct board, but in hind sight I would have made them use metal and mastic and sleeve it with insulation. I may need to just go at it this summer with a couple rolls of 4” wide mastic tape and retake large sections of it where I feel air blowing out. It’s frustrating.