Closely Spaced Tees Illegal?

Singh_4

If that is the case, I also pipe my supply
out of a c.i. boiler into a 1 1/4" x 3/4" x 1 1/4" tee , using the
3/4" run with a boiler drain for purging.
Never been questioned before.

Mark Wolff_2

Code Issues

Now that I got everyone's attention, this was brought up on another thread incidentally, but

The International Mechanical Code Book states in 1206.1.1 that "Prohibited tee application. Fluid in the supply side of a hydronic system shall not enter a tee fitting through the branch opening."

Is there anyone who is on the BOCA, ICBO, or SBCCI boards that can comment on the application of these tees for closely spaced tees in the injection circuit of a hydronics system?

The way I view it, the supply tee in line on the secondary piping is in violation of this. Anyone piping pri/sec does this every time. How do we update the code?

JB_2

tee

bull heading a tee is a no-no.

[Deleted User]

I think they mean you have to enter through the run of the tee instead of bullheading it. I wish they used more drawings in the code book.

[Deleted User]

I think what they are addressing in that statement...

are BULL HEADED TEES. This too was touched upon a while back in one of the recent threads. It also included every mans version of what constituted a bull head fitting, versus a bull headed tee.

We have been doing P/S piping since its inception and have NEVER been turned down by any of a hundred inspectors we have the opportunity to work with. I have had an inspector query me on the use of a bull headed tee that was being used in an application whereby I had two pumps pumping away from a boiler, one was for space heat, the other for DHW and the DHW pump was prioritized over the SH pump.

After I explained the theory of operation and the reasoning behind the use of a bull headed tee, he dropped the subject and signed off on the system.

I teach mechanical inspectors (IAPMO) once a year, and as I always tell them at the beginning of the class, "I do not envy you people as mechanical inspectors for having to go out into the field and look at some of these 'design as you solder' systems with a million pumps and gadgets on them to discern whether or not they comply to the codes." There is usually a loud response immediately thereafter to the affirmative.

Most inspectors walk into a mechanical room and look for items that they understand and they know are SUPPOSED to be there, like backflow prevention, relief valves, T&P relief valves, service disconnects, LWCO and so on and so forth. If they see the "minimum required" protection, they ignore the rest of the system. Some of them are former contractors, and with our systems you will see them stop and study it, but they rarely ask any questions for fear of making themselves look incompetent.

I always ask them when meeting them at a job site for inspection, "Questions?" Generally speaking, they typically make comments as to the craftsmanship, shake their head and sign the card.

Education is a long slow ongoing process, and these guys all have a different opinion of the intrepetation of the code, and they will stick by it until someone proves otherwise. And as we all know, it is written, right there in invisible ink at the bottom of every page on every code book, "Subject to field inspection authorites final intrepetation"

But I digress...

Bull headed tees have no place in a hydronic heating system, or for that fact in a potable water distribution system. Remember the "Rule of Mark's (mine, not yours) EX Brother In Law."

Water is like my EX-B.I.L., wet lazy and stupid. Given the opportunity, he will always follow the path of least resistance. If that path changes its resistance, which a pair of circuits flowing off of a bull headed tee will, then he will change his mind and his course.

Picture this in your minds eye. Water flowing out of a boiler vertically to a bull headed tee. The water flow then splits at that point, and half goes left and half goes right. Assume that both branch circuits are approximately equal in TEDL (total equivalent developed length). When the pump first starts, and the water hits the bull headed tee, half of the flow goes left, and half starts to go right, however, the person that installed the left hand part of the loop was a former plumber, and he never reams the inside of the pipes, "Waste of time, and my boss would fire me at my last job if I took the time to do so..." (real story here). So guess what, the two circuits do not have equal TEDL's, and as the water starts moving through the bull headed tee, as the flow starts picking up in the right hand circuit, the pressure drop through the left hand circuit DROPS, and the flow through the right hand circuit INCREASES, next thing you know, the flow flip flops, and the left hand circuit is now flowing more fluid than the right hand circuit, until it's presssure drop increases, and the other circuits pressure drop decreases, and guess what happens, you got it, the flow changes. This goes on for as long as the circulator is running. I call it hydraulic hunting.

Now, if the main supply flow goes to a conventionally placed tee, and 1/2 of the flow goes through the run of the tee, and one half goes through the bull of the tee, then hydraulic balance "LOCKS IN" and flow stability is in place and stays in place for the duration. It is important to note that when the two flows re-merge, that they again must mirror the supply tees in configuration. In other words, its not OK to use a proper and conventional split on the supply, but use bull headed tees where the two flows re-merge before going back to the heat source.

Got it? GOOD. Just don't EVER use a bull headed tee unless it is in a situation whereby there are two pumps, but only one would ever be running at any given time, and you and the AHJ should get along just fine...

Just for clarification, I will go whip up some simple drawings explaining this process.

ME

Mark Wolff_2

I agree...

I totally agree with your reasoning behind not using the bullhead tees. My question and the challenge I see with it, is that the code does not make any allowances or exceptions for fluid on the supply side of a hydronics system entering a tee through the branch side.

On a primary/secondary (injection) piping system, the supply and relief piping will be smaller diameter than the primary or secondary piping. The tee (not a bullhead tee) used on the secondary piping that supplies water from the primary piping is in violation of that code because it is accepting supply water to heat the secondary piping manifold. The tee on the primary pipe that is accepting the relief off the secondary piping is fine by code because it is accepting relief/return water from the secondary manifold.

Even the final drawing you posted labeled "OK if prioritized" does not meet code strictly because the code says "fluid in the supply side of a hydronic system shall not enter a tee fitting through the branch opening."

I agree that with priority pumping, the flow of the system will operate correctly, however the code doesn't allow it. Do we just ignore the codebook and get the inspectors to approve it, or is there a way we can correct the codebook to allow for this time tested and vital piping method?

[Deleted User]

Best of luck to you...

Have you ever fought City Hall?

Have you ever been called onto the carpet for doing what you perceive as being against the code in the above described sitchumikashun?

Just wondering...

ME

Mark Wolff_2

occasionally

I've had to argue code with a few inspectors, but usually I can convince them I'm right. Often times that includes giving the State Inspector a call and asking his opinion. No one has called me on this specific instance yet, but...

My one question with this whole thing is this...

How can we change the code to properly reflect common trade practice? It's not that I'm bringing this up as one of those 100 comment, nobody wins posts. I really want to see the progression of our code system to accomodate well thought out applications.

I avoid bullheading for the exact reasons you described in an earlier post, in fact I probably wouldn't have bullheaded the supply in your last drawing, but in the case of pri/sec piping, there is no other way I see to do it. I would just be interested in getting the code fixed to properly allow it. Will I keep doing it in the meantime, yes.

[Deleted User]

The code change process...

I have had a little experience in attempting to modify the International code. It required a sponsor willing to write the necessary code speak, and then that person has to appear before a committee. We got shot down on the first round, but have a better than even chance next go-round. (requiring insulation behind radiant panels and snowmelt)

One of the first questions asked on the questionairre was "What cost impact will this change have on the construction of a new home?"

Guess you can tell from that who has a deep control over the code authorities eh...(Read HBA)

If I were you, until it becomes an insurmountable issue, and I seriously doubt that it ever will, I'd suggest you just continue to roll with the punches.

If your AHJ's are any thing like mine, once they see the quality of work you do, and know you and your people on a first hand basis, they generally don't question much at all, unless it is just to satisfy the inner them.

Life is too short to waste time fighting city hall...unless it involves a potential loss of life or property.

ME

Robert O'Connor_12

Mark Wolff & 1206.1.1

The 2003 IMC Figure 1206.1.1 shows both an acceptable tee and a prohibited "bull-head" tee arrangement (at least my book does. Some books vary). Installation of bullhead connections creates excessive pressure drop, flow resistance and poor system performance. 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 the "opposite" directions. I would not read anything more into this, and or try to interpolate 1206.1.1, for it really was not intended for this kind of scrutiny regarding the P/S piping technique and you should therefore reference the manufacturer's installation instructions as they pertain to piping practices. The only "official" committee interpretations within ICC that I'm aware of have to do with Chapters 4, 5, and 6. I'm sorry to disagree with you but your interpretation of 1206.1.1 is different than mine and IMHO was never intended the way you are expressing it. The ICC allows you to submit requests for code changes and you may also petition them for a FTO (Formal Technical Opinion). If you disagree with how this code is written, I've pasted a form for your convenience.

http://www.iccsafe.org/cs/codes/pdf/publicproposalform1105.pdf


Robert O'Connor/NJ

[Deleted User]

And Mark...

This guy IS an inspector, a well respected one at that.

Thanks for the clarification Robert.

ME