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unico suppy duct leakage

I know from installing unico systems that when using high velocity systems that you are more prone to air leaks due to the higher velocity of air being moved but that is no excuse for air leakage ,if the ductwork was installed proberly the leaks would be at a mimiun ,I have used hard cast tape on all joints and seams and adjustable 90 when used ,i would think that if air leakage was such a issue one would use spriral duct and fittings but that would of course drive the jobs price up ,i have always used a mimuin of 26 gauge pipe and smoke ells and screwed and taped round pipe seams and used a hvac silcone sealant on adjustable ells and then taped with a gaskets tape usually hard cast and have never had any issues with air leakage .Things like taping abnd screwing all jointsare in my mind part of a proper install when there is alot of air leakage to me indacated a lack of attention on the installers part .Even though alot of companies throw around the word quality there main concern is quanity and money with out the 2 they would be sunk. Get a good quality gasket tape from a local hvac supply house and remove the instulation and re tape the joints including the ells if the ductwork seems oilly wipe it down with vinger to help the tape mastic join better peace and good luck clammy
R.A. Calmbacher L.L.C. HVAC
NJ Master HVAC Lic.
Mahwah, NJ
Specializing in steam and hydronic heating


  • scott w.
    scott w. Member Posts: 135
    unico supply duct leakage

    Had a great deal of air flow in the basement supply ducts of a unico system for a two story house. Complained to the contractor & he sent installer back to inspect duct work. (see previous post of June 28)When the insulation on the 90 degree bends were removed, you wouldn't believe the whistling airflow out these sections. I the home owner, helped the installer tape up all six of the 90's plus a couple of transistions. The duct is round 9 or ten inch duct. Made a noticible difference of air flow out the ducts on first floor.

    After all that, I can still feel air flow between the outside of the supply pipe and the insulation. What gives? Unico tech support says no air flow should be felt. Do the tech people operate in the real world? Will this airflow out the supply duct decrease efficiency? Is it reasonable to ask the contractor to come back again?
  • Empire_2
    Empire_2 Member Posts: 2,343

    As we have recently discussed this with , I think a Space Pak unit all duct should be sealed. Only then can the insulation be installed.

    Mike T.
  • Mark_46
    Mark_46 Member Posts: 312
    Same thing


    It's unbelievable. Your system and mine are following the same pattern. I have leakage in the area of a 'T' that the installer rechecked. There was one seem that never got taped and I figured OK that was probably it. It was taped but there is still leakage from the area. I've decided to attack it myself. It's easy enough to do and I guess the installer just doesnt get it at this point.

    But what's puzzling me at this point is how im going to pull back the insulation jacket in order to access the seems. The miniduct takeoffs are on top/through the plenum insulation jacket. So only thing I can do is cut the insulation jacket to access the seems and then reinstall. But I wonder if there are insulation jackets that use a system to close the ends...kind of like a zipper :o). Anybody know of anything? The plenum is 7" and the jacket is R6.
  • scott w.
    scott w. Member Posts: 135

    I am now in the same possition. The installer built the supply duct and pulled the insulation sleeve over the pipe as he built the circle in the basement. My only question now is should I still try to eliminate this air leakage? Will this help on the cfm's coming out the mini ducts in the rooms above
  • uni - stall
    uni - stall Member Posts: 1

    I have had a unico system for over four years and there is always a little leakage. THE KEY WORD IS "LITTLE".If you let it drive you crazy you will go nuts TRYING TO CONSTANTLY repair minor leaks. If you have ever seen the muffler tubing, it too leaks but if covered properly the leaks won't matter. us
  • A.J._3
    A.J._3 Member Posts: 4
    unico leaking

    I've installed about a dozen or so high velocity systems one of which was a unico system. I worked like a dog trying to fix all the leaks on the branch runs and I still didn't fix it a hundred percent. Lost a custuomer over it.
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    Great response Clammy....

    Awesome response clammy...

  • scott w.
    scott w. Member Posts: 135


    I will see if my heating guys will give me a roll of mastic tape and I will see if I can seal the piping to my satisfaction.

  • dixonservicecompany
    dixonservicecompany Member Posts: 1
    Air Duct leakage

    I would make sure that the air is not coming from the silver mylar liner on the out side of the flex duct. If that is not sealed it will leak real bad. The inside of the flex is NOT a air tight duct it is made to permeate into the insulation and silver out side mylar liner this is how it creates the R- value in the flex and helps stop noise. It is designed that way not a problem. just take some silver duct tape and seal it then I would go over it with a bucket mastic to complete the sealing job. That is what UNICO recommends. I am certified by unico . With a NC State H-3 license. hope this helps you.
  • Jack
    Jack Member Posts: 1,045

    "DOE Duct Leakage" and read for a while. According to the DOE the average home is loosing between 18-42% of it energy in duct leakage. Put in a new 90% eff furnace on the median duct system (30% leakage) and 90X.7= 63% system efficiency day one. Many states are requiring duct testing today and I believe it will go nationwide soon. Certainly it should. Here in CA for either new construction of retrofit the maximum leakage allowed is 6%. On commercial work if you don't pass the duct pressure test, you don't get paid. Residentially, there has been no requirement for testing and the existing stock of ducted systems in incredibly deficient. I spoke with a contractor who did a 12 outlet single story raised ranch duct repair. Two men 1.5 days, $2500 and then the homeowner had to buy the new equipment. Another contractor up in Nevada repaired a big houses duct. He said it was over 10 grand.

    I've felt for a long time that this is the "crazy Aunt in the back room" that the industry never talks about. The unitary manuf can put all the technology they want in the box. They just can't deliver it because of the incredibly poor duct work. This is an enormous black eye for the industry.
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