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International Mechanical Code & Hydronic Tees

Dave E.
Dave E. Member Posts: 9
I think I must be misunderstanding this, or else it seems to outlaw diverter tees. I suppose the branch opening must be the middle opening. But then, the illustrations I've seen of the main riser from a boiler connected to the middle opening of a tee, one side to a boiler drain and the other supplying the radiation, seem to be against this code. So I still don't know what's up.


  • Dave E.
    Dave E. Member Posts: 9
    Code Limitation on Tees

    While tinkering with my water boiler hydronic piping and reading my 2003 International Residential Code (which consists of sections of other International codes) I ran accross:

    "M2101.7 Prohibited tee applications.Fluid in the supply side of a hydronic system shall not enter a tee fitting through the branch opening."

    Does anyone know the reason for this? I thought it would be a good way to put a gauge in the line if I ran the supply through the branch openings and used the middle opening for the gauge.
  • bruce_21
    bruce_21 Member Posts: 241

    I think this means bullheading a tee on the supply is outlawed. "shall not enter a tee through the branch"
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    That's a prohibition against attempting to equally split flow via supply through the branch of a tee. The "middle" opening is the branch and such is perfectly suited for mounting a gauge.
  • [Deleted User]
    NO BULL...

    headed tee's allowed.

    Exceptions include primary secondary applications, variable speed injection applications, and diverted prioritized flow considerations.

    I attempted to write a clarification to the IMC regarding this statement, only to be told that all references to it were yanked in the new code.

    Guess the enforcers couldn't interpret it either :-)

  • Robert O'Connor_12
    Robert O'Connor_12 Member Posts: 728
    Section 1206.1.1

    If your IMC has figure 1206.1.1 on the next page, as others have posted it is perfectly code compliant to install a gauge in the branch (bull) connection. The figure will make you aware as to this sections meaning.

    1206.1.1 shows both an acceptable tee and a prohibited bull-head tee arrangement. Installation of bullhead connections creates excessive pressure drop, flow resistance and poor system perormance. The intent is to prevent supply-side fluid flow from entering the side (branch) opening of a tee when that opening connects to a main, and the straight-through (run) opening of the tee are used as branch connections flowing in opposite directions.

    Hope this helps!

    Robert O'Connor/NJ
  • Dave E.
    Dave E. Member Posts: 9

    Thanks, I'm using the International Residential Code for One- and Two-Family Dwellings, which omits figure 1206.1.1
    Now I know.
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