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Smoke pipe question. Seam up or down?

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old wrench
old wrench Member Posts: 14
Talking to someone today about smoke pipe/ vent connector. When I was a young lad years ago we always put the smoke pipe seam down (maybe because grandpa did). Looked in the IRC and Fuel gas code but no mention of it anywhere. I would love to find a link from a manufacturer with anything on this.

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  • ChrisJ
    ChrisJ Member Posts: 15,793
    edited January 2020
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    As far as I know, male facing the direction the exhaust is going. So the appliance would be male and chimney female.

    Wood stoves are the opposite to keep condensation and creosote from running out of the pipe.

    Unless you mean the locking seam on the side of the pipe? I don't think anyone cares about that one.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • CTOilHeat
    CTOilHeat Member Posts: 56
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    I've always run smoke pipe with the seam down, or facing the wall on a vertical section.

    Reasoning for me has always been that the seam looks best when you don't see it.
    old wrench
  • Intplm.
    Intplm. Member Posts: 2,011
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    Seam down.
    And if by some odd happening the seam splits open, the seam will be down but smoke will be less to leak as the seam is down and not up. Or so it has been said.
    old wrench
  • old wrench
    old wrench Member Posts: 14
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    Years ago I thought it was something like this as well, seam always went down on vertical run. Trying to find something in writing that shows this?
    Intplm.
  • Ironman
    Ironman Member Posts: 7,379
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    Down, but only for looks.
    A cat 1 vent should always be in a negative pressure, so it shouldn't matter which way the seam faces.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    STEVEusaPA
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,635
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    I usually put the seam down but don't think it matters.

    I used to find a lot of flue pipe with few screws and poorley secured. One of my fears was a smoke pipe falling down or becoming disconnected. No protection against that (except for smoke detectors)

    I usually put at least 3 screws in every joint and on larger sizes I shoot a few screws right through the Pittsburgh lock on the seam
  • MikeL_2
    MikeL_2 Member Posts: 498
    edited January 2020
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    We put 3 screws in each joint and reinforce our smoke pipe installs with sheet metal drive cleats......
    SuperTechSolid_Fuel_Man
  • MikeL_2
    MikeL_2 Member Posts: 498
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    Drive cleats make great hangers & straps......
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    What's smoke pipe, never heard of it (jk). I've heard of flue pipe.

    Terms like 'smoke pipe', jet line, blast tube, soot saw, soot vacuum, give the impression of a heating system that's dirty, and loud, and needs constant cleaning.
    They are kindler, gentler (cleaner, quieter) oil burners now...

    @MikeL_2 as far as the drive cleats, I do like the one at the chimney base, but the others look like both overkill and like you're trying to prevent an explosion from blowing off the flue pipe. Does that happen often in your area? I do like the nice bead of sealant over a foil tape mess at the damper.
    Of course 3 properly placed screws (code) in each joint.

    As far as seam, usually up except for the piece with the draft regulator, then that seam is opposite the center of the regulator.

    There was an error rendering this rich post.

  • Gordy
    Gordy Member Posts: 9,546
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    Venting of hvac shouldn’t technically matter. Like @Ironman said it should be negative pressure. So male up seems to be choice.
    Wood burner different story. Male end down assures creosote does not leak from the joints.
  • HVACNUT
    HVACNUT Member Posts: 5,865
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    To me, if two seams are next to each other, it leaves too large a gap. I stagger the seams. And why do I need to re crimp a factory crimp?
  • EzzyT
    EzzyT Member Posts: 1,296
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    I’m ocd so when we do pipe flue pipe the seems and screws have to match up and seams are always faced down or towards the wall.
    E-Travis Mechanical LLC
    Etravismechanical@gmail.com
    201-887-8856
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,338
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    Hi, I decided to look it up: Definition of smoke pipe : a usually thin metal pipe connecting a possible source of smoke to a chimney or smokestack. Seems pretty all inclusive o:)
    As I deal with non-condensing gas mostly, I'm in the habit of facing the seam up. This prevents the condensate that forms on startup from dripping out the seam. I don't think I've ever seen anything in code about how it should be.

    Yours, Larry
    rick in Alaska
  • MikeL_2
    MikeL_2 Member Posts: 498
    edited January 2020
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    Steveusa,
    I consider myself lucky to have apprenticed ( starting in the late 60's ) in a shop that did plumbing, hvac, hydronic heating, and sheet metal fabrication. Along with a variety of trade skills, I absorbed the local lingo.
    Wholesaler counter reps, manufacturers reps, salesmen & women, journeymen, related trades people, and all others I came in contact with knew what smoke pipe was; at that time there was never any confusion, or a proposal for a name change.
    As far as overkill & explosions; it takes an extra 15 minutes or so to beef up an install with a back strap. Keeping adjustable fittings aligned, level, and plumb, and, added protection from a bump or bruise is my goal. Explosions are not common here and I'm certain my installs are not explosion proof. My fastening method does help prevent adjustable elbow rolled seam failure..........
    STEVEusaPA