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Thread: Duct fittings question

  1. #1
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    Duct fittings question

    On many, not all, DC duct setup drops I see a wye (sp) followed by what must be a 45.
    I'm wondering why a fitting made with a straight end and a long sweep 90 isn't used instead.
    Is the reason cost (they are pricy) or is there some other reason?

    Looks to me like the long sweep drop would flow much better.

  2. #2
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    The answer is likely that there is no way to pre-ascertain what the angle needs to be, so a wye is a compromise. What you suggest absolutely could be fabricated custom (assuming metal here of course) but would also as you note, require quite a few shekels in payment.
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    The most expensive tool is the one you buy "cheaply" and often...

  3. #3
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    For metal ducting, what typically follows the wye is an adjustable elbow (at least in my setup) which can basically be adjusted to any angle between zero and 90 degrees. The adjustability of the elbow is a real god-send to get everything lined up without too much fuss.
    There is a very fine line between “hobby” and “mental illness.” - Dave Barry

  4. #4
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    This is what I'm referring to.
    Much better flow, I would think, over a wye and a 45 if you are going straight down.
    Many setups I've seen use a wye, then a 45.
    Attached Images Attached Images

  5. #5
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    A lot of the sewage piping in my house was done using not the sanitary tees and elbows. What they used was fine for air vents but plugged up with liquids. I have replaced everything that is not cast iron. The wrong stuff was all threaded pipe. I bet they do not make cast iron in tight radius fittings.
    I aslo realize cast iron has some degree of adjustability before the lead is poured to lock it into place.
    Bil lD

  6. #6
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    Quote Originally Posted by Bill Jobe View Post
    This is what I'm referring to.
    Much better flow, I would think, over a wye and a 45 if you are going straight down.
    Many setups I've seen use a wye, then a 45.
    I don't think I've ever seen anything like that in "large" diameter pipe. I could be fabricated using a piece of straight pipe and a long radius elbow if one is available provided you can calculate the cut lines to make a saddle joint using the appropriate solvent-adhesive.
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  7. #7
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    https://www.zoro.com/search?q=45%20D...%20Elbow%20Wye
    not cheap this way, would be a smoother flow
    here is a 14" for $1019.99
    https://www.supplyhouse.com/Spears-3...45-Elbow-Combo
    they are out there lots of money

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  10. #10
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    The ABS should be fine as long as the diameters match up so it slides together correctly. Try to get the exact specifications.
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  11. #11
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    I wrote to them. I'll post when I hear back.

    Check out the retail price and their price.

  12. #12
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    You're getting into the price for "really nice, modular metal" fittings there, Bill... (Nordfab)
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    The most expensive tool is the one you buy "cheaply" and often...

  13. #13
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    Well, I called them and was told they know nothing about compatibility with PVC wdv.
    No tech department to talk to....nothing.

    Does anyone here know if abs dwv and PVC dwv fit one another?
    Yes,the cost would be slightly higher, the fitting being $75, but a wye and a short piece of 6", then a 45 would cost close to half of that.
    I believe the better flow would eventually make up for it.
    I'm referring to the abs fitting I posted a link to above. Post #9.
    $9 shipping.
    Last edited by Bill Jobe; 12-05-2019 at 11:05 AM.

  14. #14
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    There is a glue that joins ABS to PVC. You can even find it in Lowes, or HD. Sizes are the same.

  15. #15
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    I called Lowe's and the guy in plumbing said he didn't know.
    Tom, are you saying the abs fitting at the link will fit schedual 20 or 30 PVC dwv pipe?

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