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Unico: Preferred main trunk material

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ChrisL
ChrisL Member Posts: 121
Thanks for all the tips. I am going to price out the spiral duct tomorrow.

Chris

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  • ChrisL
    ChrisL Member Posts: 121
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    Unico: Preferred main trunk material

    I am going to be installing my first Unico AC system. Could anyone provide any advice on what is the best material to use for the trunkline, and any other tips.

    Thanks,

    Chris
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    Spiral Manufacturing makes ductwork extremely well suited to high-velocity applications. Their catalog is truly exceptional and it's wonderfully easy to specify custom fittings in ways that nearly eliminate mistakes. I was truly shocked at their quick turnaround--just a few days including a number of custom fittings. If you don't already do you sheet metal in-house, I found the price surprisingly competitive. My first high-velocity system is so tight that I believe it could actually hold water.
  • bill nye_3
    bill nye_3 Member Posts: 307
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    7\" round

    Seven inch round duct in five foot lengths would have to be the fastest and least expensive. Get the insulation that slides right over the pipe. 2" hole saw for your take offs.

    I did the duct board and the round fiber duct. I found the metal 7" the fastest to assemble and hang or support. But I'm just an oil burner guy and we often known for being rather crude.

    I tape all the seams and connections with aluminum tape. You can pre-assemble out in the open and feed it into the installation area if you have enough access
  • Brad White
    Brad White Member Posts: 2,398
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    Ducting

    I second Mike T.'s use of Spiral Co. ductwork. Nice folks from Minnesota, Yah.

    Rather than aluminum tape, I would use Hardcast Iron Grip or other brush-on commercial duct sealant. The higher pressure makes sealing more critical, not just for higher leakage potential but for noise.

    The old dual-duct systems installed in the 30's, 40's and even into the 70's had very well sealed ductwork for this reason, noise not so much as energy.

    Seal all joints, screw holes, all the way around, well before insulating. Let it set first and run the unit to test for leaks. If you can hear or feel a leak, seal it. Retest and insulate.

    You may find that a loop or ring duct (versus dead-end duct mains) will give very good balancing and airflow characteristics, if logistics allow this.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
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    In addition...

    not rather than aluminum tape
  • Brad White
    Brad White Member Posts: 2,398
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    Instead of

    aluminum tape.... which has an adhesive which is weaker than the Iron Grip duct sealant... my $0.02 anyway. I suppose no harm.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Saggs
    Saggs Member Posts: 174
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    we put 2 unico systems in an old dental office w/ drops up through 4" of hardwood floor. Not an easy install. We used 7" 26ga pipe in 5' sections and ductsealed all lateral seams and joints then wrapped the ductwork in foil-bubble wrap. The 2" takeoffs get drilled right thru the insulation and are a breeze. Use a little wd40 on the hole saw and it cuts much faster. I have tried foil tape on the seams but the hi velocity and cold air made it fail. This system was in a cool basement so ductwork only needed the foil wrap.
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