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arrangement of closely spaced tees for primary-secondary

As I study diagrams, explanations, and some pictures of beautiful installations here, I see 'closely spaced tees' set up with the primary on the runs, and the secondary on the branches, and sometimes vice versa - almost always with both tee branches pointing the same direction.

How important, if at all, is the orientation of the tees?

I'm trying to design a piping layout for a space smaller than I would desire, under and around a Triangle Tube Excellence. The primary will be 1" copper, as will the secondary, then zone valve'd branches to 3/4" baseboard loops.

One layout that occurs to me I haven't seen in use - with the primary and secondary arranged as an 'H' - if that description makes sense....

In other words, the 1" primary supply enters the run of one tee, and the secondary supply leaves by the other run of that tee; with the primary and secondary returns on the runs of the other tee; and of course, the branches tied together facing each other to provide the 'short circuit' that separates the loops.

This 'H' arrangement would help for a compact but serviceable layout - but would the fluid dynamics be 'wrong' ?

Thanks for any thoughts



  • siggy
    siggy Member Posts: 79
    closely spaced tees

    Don't arrange the tees in an "H" pattern. You will find that fluid momentum from the primary will induce flow in the secondary. Rule of thumb is to have 8 pipe diameters of straight pipe leading into the run of the upstream tee, and at least 4 pipe diameters downstream of the second tee. The bulls of the tees can face in any direction. See attached illustration.

    Hope this helps.

  • Bob Vennerbeck
    Bob Vennerbeck Member Posts: 105
    closely spaced tees

    Thanks for prompt and authoritative response - it's not the answer I wanted to hear, but it is the one I expected... something didn't feel quite right about my 'brainstorm' arrangement.

    Gotta love the Wall !

  • HVACdavey
    HVACdavey Member Posts: 1
    DAN HELP!!

    I was under the impression that what goes into a tee must come out..... if you use the H lay out for your closely spaced tee's and your bull's are facing each other the common piping between your tee's (under 6 inches in length) should provide less resistance than your system side for proper flow back to the lowest pressure (the suction side of your primary pump) I would really like to know if my understanding is accurate.
  • icesailor
    icesailor Member Posts: 7,265

    Thanks for saying that.

    I've pointed that out for years and when I do, I get the glazed eye look.
  • icesailor
    icesailor Member Posts: 7,265
    It doesn't.

    It doesn't. You have to have the secondary tees far enough away from the ells to get away from the turbulence of the turning fluid.