Bullhead T. Is it really bad????

STEAM DOCTOR

Hi to all. More hypothetical than anything else. I've always been taught that never have steam entering the bull of a T. Will cause Steam and condensate to bounce back and cause all sorts of trouble. Just had a moment of clarity today. Every single boiler header that utilizes two risers, has a bullhead T built right into the header. I am probably missing something but looking forward to the discussion. Thanks to all

ChrisJ

STEAM DOCTOR said:

Hi to all. More hypothetical than anything else. I've always been taught that never have steam entering the bull of a T. Will cause Steam and condensate to bounce back and cause all sorts of trouble. Just had a moment of clarity today. Every single boiler header that utilizes two risers, has a bullhead T built right into the header. I am probably missing something but looking forward to the discussion. Thanks to all

The steam is flowing thru that tee in one direction, towards the mains and equalizer, no?

SgtMaj

My response would be “ it depends”. There that should clear things up. I think the system near boiler piping would need to be very big, additionally the system would have to be perfectly balanced and very low pressure, maybe in ounces which would allow the condensate to flow back to the boiler. Maybe a combination of counterflow and parallel flow system? Maybe. But getting the perfectly balanced system would be the key and almost next to impossible, there’s a lot of math involved with that.

ethicalpaul

The bullhead tee runs into the header, but that's not the direction the steam flows.

Now imagine the header ends into the head of the tee and goes up to the main and goes down to the equalizer (a pattern we have seen many times).

In this case, the theory goes, the water and steam will go into the tee and hit the back wall of it and some water will go up with the steam.

In reality, I don't think it matters much. Unless the water is garbage, it won't be surging into the header anyway, and the steam alone doesn't care about such things.

At residential flow rates, the steam goes where it goes with little or no resistance.

Jamie Hall

Kind of complicated. On a header, usually you have some steam flowing in one arm, some steam (more or less same volume, and the combined flow going out the other arm. Not really a bullhead arrangement. The arrangement where you can and do get some turbulence is where either both arms are flowing in or both arms are flowing out. Then yes, there can be some turbulence there. Main thing is greater head loss with that arrangement -- but that's not usually a big deal, and in either case the advantage (sometimes!_ is that the head loss to both arms or from both arms, as the case may be, is equal. An arrangement which can give some balancing trouble is that one with some flow coming in the bull and some from one arm, or going out the bull and going out one arm. Then the straight through flow will have considerably less headloss than the flow from the arm to the bull (or the other way around). Not a factor for a header, or in most steam applications, but can be a problem with balancing hydronics.

STEAM DOCTOR

Thanks everyone. My fog is starting to clear!

ethicalpaul

What is the head loss of a residential steam system when the steam readily flows through it even when there is only an inch of water column pressure?

I think it's immeasurably small.

EBEBRATT-Ed

Headers and risers are oversized to keep the velocity down so the "bull head" isn't as much of an issue.

Steam mains etc are sized with a higher velocity so there is the need to avoid bull heads in those pipes.

That is why they say to avoid a bull head at the end of a main with the vent on top and the drip at the bottom.

But a lot of them are done that way and they work if the velocity is low enough.

ethicalpaul

But at the end of the main, the main vent will close shortly after the steam hits it, and then it's just a dead end to the steam anyway

clammy

Here’s my take on it ,if you have a say 2 inch bull head tee being feed w a 2 inch riser off a header . If your 2 mains are 2 inch should not the riser be sized to feed both mains ,you would think so if all you have is a a single riser feeding two mains I believe you would end up w some carry over condensate or wet steam due to velocity increase due to riser sizing being smaller then the connected load cause a slight Venturi effect I would think . I think the true test of the effects of a bull head tee is the quality of the steam being wet non dry steam will condense quicker leading to a system that can be difficult to balance due to issue discussed above . On small system where say even a 1 1/2 main would handle the edr fine the issue comes into play on mains which are close to there max edr and are bulled off a single riser ,this is where separating the bull tee and piping each main w there own riser off the header makes the difference . But as I always say steam is the most forgiving of all systems to a point w just about zero moving parts just steam the rest is basic physics . The most difficult part of a steam system aside from making people believe that all the magic happens in the near boiler piping and that instruction should be followed is that it truely is the most forgiving and that when correctly installed nothing beats it usually quite and undetected operation supply just comfort and also nothing can dump so many Btu s into one space so quietly to heat the oldest leakiest homes built . Try that w a wind blowing hot air furnace and see how comfortable you are while you have air blowing across your skin ? And the cost difference being w either hot or hot water your powering some thing to move the heat 3/4 to 1 hp blower motor or a fractional wet rotor circulator or better yet a 24 volt transformer the rest is done w basic physics .
Bull head tee remain because guys are to lazy to smash them out and repipe plus most are afraid due to the cost that they think they wont get the job due to the related price increase . Personally I straighten it out it’s in the price ,if you don’t like the price we’ll keep you bull heads and have some one else do the job simple as that . There’s things that jump out when I look at steam system w issues and I tell it like it is ,now if your willing to live w it that fine but I’m not going to dilly dally and waste my time trying to straighten out or get a system to operate correctly when garbage piping is really the cause and a cheapness to correct is what keep it working like crap . This is not my issue being it’s not my home and I do not have to live w it . I know this may seem off base but it’s not . It comes down to $ one person pays and another receives and work being done . Lips moving usually get zero accomplished .
Peace and good luck clammy

STEAM DOCTOR

Thanks @clammy. Just to clarify, my purpose of this discussion is purely academic. I have no intention of installing bullhead tees. Or allowing the existing ones to remain on jobs that I do. Your point is well taken about a single 2 inch riser feeding 2 2-inch mains. But as always need to crunch the numbers. Sometimes a 2-in riser can handle the BTU load. Sometimes not. Doesn't inherently matter how many mains it's feeding. Matters how many BTUs are going through that riser. And there is also a difference between a vertical 2-in pipe and a horizontal 2 inch pipe. Vertical is always more forgiving and has higher capacity.

Chris_L

I can't speak to the theory. But for 30 years I've had two steam boilers with single risers feeding two mains through bullheaded Ts. Here is one:

That is a 2" riser feeding two 1.5" mains. The other system is the same except that one of the mains is 2". They are relatively small boilers, 266 and 356 sq feet, respectively.

They both work fine. I don't have any reason to believe the Ts are drawing condensate into the mains. Where would it come from? The headers several feet below? There shouldn't be much if any there in the first place, especially after start-up.

If I ever have to replace these boilers, I'll likely have the bullheaded Ts removed, but I am unconvinced it will improve anything.

EBEBRATT-Ed

@ethicalpaul

At the end of the steam main with a vent and a drip when the vent closes there is basically no flow in that main so there is nothing to smash. Any steam pressure is pushing at the vent and at the water in the drip. But the velocity and flow has basically stopped.

ethicalpaul

That's what I'm saying in response to:

That is why they say to avoid a bull head at the end of a main with the vent on top and the drip at the bottom.

So a bullhead tee in this position causes no harm.

EdTheHeaterMan

ethicalpaul said:

What is the head loss of a residential steam system when the steam readily flows through it even when there is only an inch of water column pressure?

I think it's immeasurably small.

I Think that Paul needs to have a better measuring tool. I know for a fact that if you are using a vacuum gauge that measures only In.Hg. (not microns) on drawing a vacuum on a refrigerant system, then it is like building a house where the only ruler on the job site is the odometer on the work van that delivered the lumber.

I'm sure you can do a video in what tools you need to measure immeasurable steam pressure drop thru a small residential one pipe steam plant in New Jersey. You can measure inches of water column with a column of water in a U shaped tube.

If you have that tube on a 1' per ft. incline, you can measure fractions of an inch of water column. And if you have that tube on a 1" per yard incline, then you can measure fractions of those fractions of an inch. What if you have an 1" inclined tube the length of Paul's basementn. now that would be a cool video to watch. How I measure, immeasurable pressure changes with mu home made inclined manometer.

ethicalpaul

I don't measure in inches of Mercury, I measure in inches (and fractions) of water column.

I am soon going to open the end of my main for a modification, when I do that maybe I'll make you that video

And yes, my system is small, but so are my pipes. Larger systems have larger pipes so it's rather comparable.

SgtMaj

@EBEBRATT-Ed I think there is still plenty of steam movement until those radiator vents close, is it “basically no flow”, i suppose that’s a relative term.

ethicalpaul

SgtMaj said:

@EBEBRATT-Ed I think there is still plenty of steam movement until those radiator vents close, is it “basically no flow”, i suppose that’s a relative term.

But not at the main vent there's no steam movement after the main vent closes.

In rest of the main of course there is plenty of movement before and after the radiator vents close