Understanding bull headed tees and flow supplied from branch

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Rossn, Apr 15, 2021.

  1. Rossn

    Rossn Member

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    For domestic water plumbing is it considered acceptable to have supply flow enter a standard tee from the branch side? Maybe it is location dependent (fixture supply, at a double lav vanity versus at a main branch)?

    I was taught by an old-school hydronics guy that a bull headed tee was when the flow entered from the branch side (no reference to a larger branch than run)... and it seems that per IMC 1206.1.1 - in hydronics flow is not allowed to enter through the branch. He seemed to think one should not enter the branch in domestic water plumbing, either.

    It seems that plumbers not working in hydronics refer to a bull headed tee as one with a larger branch than the runs.

    I saw an example in the IPC that showed flow coming into the branch of a standard tee.
     
    Last edited: Apr 15, 2021
  2. Sylvan

    Sylvan Still learning

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    For some reason, most plumbers try not to use a bull tee including me
     
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  4. Rossn

    Rossn Member

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    Thanks, Sylvan. Do you lump into that comment using a standard tee with flow in through the branch, or just the tee with the larger branch?
     
  5. Mr tee

    Mr tee In the Trades

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    I never hesitated to use a bullhead tee (of either definition) when if simplified the design of a water or gas system.
     
  6. Tuttles Revenge

    Tuttles Revenge In the Trades

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    I'm with Mr Tee on this.. tho I was taught not to use a bull head tee, there was no reasoning behind it..
     
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  7. gsmith22

    gsmith22 Active Member

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    all fittings have pressure losses. You can kind of idealize the pressure loss to be similar to two 90 degree bends if flow is coming in through the branch side splitting into flow to the left and right. Its obviously worse than two single 90 degree bends because you don't have the outer pipe wall guiding the flow around a turn. The flow dead ends into the perpendicular wall so if there is a reason to avoid its probably that. The result is a lot of turbulence and resulting pressure loss trying to get the flow to change direction after it smacks into the pipe wall. If a tee with flow coming in through the branch is what works for the layout, I don't see why it would be frowned upon other than recognizing that it will be a big pressure loss and potentially with high enough velocity, maybe there is an erosion issue where the flow dead ends into the pipe wall? Its certainly not the most flow friendly method of plumbing.
     
  8. Rossn

    Rossn Member

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    thanks all for confirming while best to avoid, not an absolute no-no when it comes to less critical areas (i.e. further down the branch). It sounds like this is a more sensitive topic in hydronics, where pumps may be triggering on and off, and varying flow.

    Agreed with gsmith22 that the losses are from the flow being less laminar, and more turbulent in nature, but good to know it isn't known to lead to certain failure/problems, etc.

    Thanks for weighing in!
     
  9. wwhitney

    wwhitney Well-Known Member

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    Some info from the Copper Tube Handbook is below.

    It doesn't explicitly give the equivalent feet for the "bullhead" path through a tee. But I think we can assume it is at least the same as the "side branch" equivalent length, maybe even more. Which in all cases is notably more than the 90 degree ell equivalent length.

    So it would appear that if you have a supply you wish to split into two, with each heading out at 90 degrees, there's an advantage to using a tee normally, with a 90 degree elbow on the straight outlet.

    But if you need the split supplies to be geometrically on the same line, the bullhead tee is obviously much simpler. And while the data below gives a presumable lower bound on the hydraulic "cost" of doing that, I haven't found any explicit data on the equivalent length for a tee in a bullhead configuration.

    Cheers, Wayne


    Capture.JPG
     
  10. Sylvan

    Sylvan Still learning

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    Not so much with a standard tee.

    The velocity increase through the smaller piping can cause excessive noise and in copper especially on hot water erosion is possible because of the increased turbulence the water goes from big to small just like a reducing ell
     
  11. Jeff H Young

    Jeff H Young In the Trades

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    I've bull headed water and gas a million times I still wont hesitate on gas. Changed my ways a little and on certain piping I'll avoid the bullhead especially working for other contractors. there are a long list of practices that you never know how others will approve and sometimes I don't want to rock the boat defend why I do it a certain way, like putting an ice maker box in upside down . You'll get chastised for wasting fittings and time coming down from the top and wasting 2 90s or called an idiot for putting it on upside down , something is going to happen to the valve stem sediment or something can't win
     
  12. Rossn

    Rossn Member

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    Thanks, guys! Clearly not a right or wrong, thing, but avoid when reasonable.

    One of the things that prompted the question after thinking I should not do this was the below example from IPC (2015, 2018) Section E103. They actually show the configuration of flow coming in the branch of the tee, which had me scratching my head after hearing from the hydronics old timer to not do that.

    Walking their example (which seems to have a few errors), it seems like using straight run vs. side branch length equivalents is not based on where the flow exits the tee (both places), rather where it is entering the tee. Do I have that right? Branch length equivalents for side branch is for when flow enters the side branch as we have been discussing, not when it exits the side branch, as one of the two directions?

    upload_2021-4-15_20-55-46.png
     
    Last edited: Apr 15, 2021
  13. Rossn

    Rossn Member

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    By 'Bullhead configuration' do you mean a tee with a physical larger branch, or do you mean flow coming in the branch (of a normal tee)?
     
  14. Jeff H Young

    Jeff H Young In the Trades

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    bullhead means flow enters the side of the tee
     
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