2 risers compared to 1 on steam boiler?

AndythePlumber · January 3

I was always taught, and the manual usually shows; using two risers off your boiler is better than one. Often it’s mandated by the installation manual. If space allows I always use two and do not restrict the tapping size. especially after you get past say 4 sections. Not sure exact cutoff at the time of this posting.

well if you read the wm lgb manual. Up to an lgb-12 (3600sq ft steam) go ahead and use a single 6” riser. My question is. Why is Weil McLain ok with it but other manufacturers are not. What am I missing? Also, bonus points. What does “lgb” mean in the context of boilers

Mad Dog_2 · January 3

That's what their engineers designed & tested on. You can never go wrong upsizing to the next size. If I can't use both tappings, or it makes more sense I'll use one and blow up to next size immediately. Mad Dog

clammy · January 3

I have always noticed the some times drastic different header sizes from different boiler manufactures and i boil it down to the smaller the header they suggest the better for the contractor to save money .Smaller pipes smaller fitting and a lot of guy feel this way the manufactures giving the go ahead for smaller piping and header instead of doing the math and figuring the exit velocity in correspondence to riser and header size for them selfs. Usually if you do the math you would always be incline to increase header size and never reduce a supply riser cause the math doesn t lie being it not in a competition w other manufactures over a race to the bottom over increased pipe size and increased material costs .

peace and good luck clammy

ethicalpaul · January 3

the manufacturer’s engineers did the math. Trust them. They have no reason to specify something that will fail. Some configurations will have slower velocity than others, due to the combination of size and number of supplies, but you can trust them all to work fine.

I have a couple videos about this, but in this one I throttle the supply WAY down with a valve and you can see the steam still flows.

Steam is very compressible and it can go through even undersized piping just fine.

Most surging issues are caused by water quality. Even ridiculously incorrectly piped boilers can perform fine

Going beyond the manufacturer’s recs is just needlessly wasting someone’s money, but the markup is appealing, no doubt

Unfortunately those overpriced boiler replacements are what makes homeowners want to rip out steam systems.

Long Beach Ed · January 3

Sometimes you want a slower velocity because of other inadequacies of the system. Sometimes you know the manufacturer permits a ridiculously unfavorable high velocity in their minimum recommendations.

Riser selection is part of the system designer's expertise and experience. The manufacturers' recommendations are just that: recommendations. The engineer is expected to engineer. Otherwise, he's just a fitter.

ethicalpaul · January 3

@Long Beach Ed on this forum we see time and again that licensed professionals can’t even be bothered to look at a simple piping diagram in a short manual that comes with every boiler.

And yet you expect them to do the engineering to determine that the manufacturer’s guidelines, in the manual that we know they don’t open, are insufficient?

Come now

TKPK · January 3

curious,

I know bigger and multiple tappings slows down the steam and produces higher quality/dryer steam which is better for the entire system.

But, how much would a double drop header delay steam from heating up the entire main / increase the burn time in each cycle?

My system burns 15 minutes every 75 in “normal” conditions. Everything is well insulated on supply and return and all the NBP gets down to 130F or lower range and the ends of the main get down to 70-80F. I pay to heat that mass every time (some is useful heat). Maybe that increases to 16-17 minutes on average?

At some point bigger is not better in start up investment or operating cost. You want big enough but not too big. Mfg spec would seem to me to be the smallest AND the biggest you would want unless you have a good reason to diverge. Just like people putting in bigger boilers rather than matching EDR

ethicalpaul · January 3

Now to be fair to licensed hvac professionals, they are not engineers. That’s why the manual exists.

There’s no shame in not being an engineer, and following the manual, and if anyone can show me a boiler installed as per the manual that does not perform correctly I’d really like to see it, but I’m not holding my breath, that’s for sure

Long Beach Ed · January 3

https://forum.heatinghelp.com/discussion/comment/1831705#Comment_1831705

We're assuming a qualified and competent designer. All bets are off when you hire a yahoo.

ChrisJ · January 3

I'm not an expert but I would think the maximum allowed velocity would have to do with how far the water is from the exit on the boiler. The further the opening is from the water the higher the velocity it would tolerate.

I'd expect the manufacturer to know their product.

ethicalpaul · January 3

https://forum.heatinghelp.com/discussion/comment/1831714#Comment_1831714

a trained, experienced, licensed, bonded, and insured yahoo, that no homeowner has the information to determine

Long Beach Ed · January 3

https://forum.heatinghelp.com/discussion/comment/1831720#Comment_1831720

Doesn't the same apply to any professional? Doctors? Lawyers? Lots of them suck too… but their customers are less likely to choose them by low bidder. eh, maybe not.

ethicalpaul · January 3

Yes, bad professionals exist in all professions, but we were talking about whether manufacturers' guidelines in a boiler manual can be trusted.

If we saw a doctor perform surgery like some of these boiler installs, a person looking to have an appendectomy would have had their stomach removed and that doctor would get sued. We rarely or never see boiler installers punished or de-licensed for their negligence.

Mad Dog_2 · January 3

Ill take the opinion of a Surgeon, plumber, Brick Mason, Attorney, et cetera with decades of actual experience over Armchair pundits & tinkerers. We know what works, what don't, and what's best. Mad Dog

Long Beach Ed · January 3

"The manufacturer's minimum recommendations should work in the vast majority of installations."

"

ethicalpaul · January 3

https://forum.heatinghelp.com/discussion/comment/1831735#Comment_1831735

My chair didn't install my boiler, I did.

ChrisJ · January 3

https://forum.heatinghelp.com/discussion/comment/1831735#Comment_1831735

You know the sad part is, all of those guys installing them completely wrong aren't making the "Armchair pundits & tinkerers" look bad.

But they are making the good pros look bad. They're making the life of every good pro out there harder and more difficult. If they could only follow instructions….even the minimum ones.

Mad Dog_2 · January 3

How many years did you spend having "pros" direct you and then diddling on that ONE boiler of yours? Are you ready to do a boiler a day and hang out a shingle now? When does the "Ethical? Paul: National Seminar rubber chicken lecture circuit start? Any professional trade licenses? Certifications? Books authored?

It's easy to be so cocksure & smug when actual pros & a brilliant authors writing & books "held" the wrenches and "Turned" them for you and you had the extreme luxury of unlimited time and no deadlines to or annoyed homeowners who want you in and out to contend with.

We see the worst of the worst installations here and the slovenly "pros." deserve all the abuse, scorn & ridicule we give them. However, there are many, many good contractors that don't come here and they do a decent & honorable job. Your broad brush condemnation of "Pros" does not reflect reality. You made an award winning cake in your basement....try doing that everyday to pay your bills.

I commend your efforts to a point, but don't ya think The Endless Victory Lap-Marathon in your case ran its course a long time ago? Mad Dog

ethicalpaul · January 3

If my actions on this forum have given you this impression, then I apologize. I've said repeatedly that I could never have understood steam heat without this forum and the people on it. You can see that history in my discussion posts.

I am aware of the many great contractors out there, but as you said, we usually see the evidence of the other ones on this forum.

This post is going a bit awry having started out about 1 vs 2 supply pipes. I will, with your kind permission, continue to try to help others who come here just like I did in 2018, with no idea how steam heat works.

ChrisJ · January 3

Long Beach Ed · January 3

I believe this forum already has a fairly qualified moderator.

EBEBRATT-Ed · January 3

If everyone just followed the MFG piping requirements and skimmed the boiler properly there would be few problems.

There are DIY hacks and professional hacks to be sure. That will never change except by education. Since it has been proven that these hacks have proven they do not read (or cannot read) the manual or skim the boiler or use copper on steam headers this will probably never change.

The contractors I dislike are the ones that "have done it that way for 30, 40, 50, years" Yup you did, and you have done it wrong the whole time.

I know I installed steam boilers (and probably everything else) wrong in my early years.

That's why we are all here to learn.

I haven't met anyone yet that knows everything

AndythePlumber · January 3

you guys are awesome. As always I have gotten my answer in abundance. I am a professional licensed yadi yadi with 20 years experience. I have seen countless “pros” that are just plain inadequate. It’s no news. I have also never seen a pro put in sight glasses on a steam header to actually dig deep and see what’s going on. When I saw some of your videos ethical I was seriously impressed. I love them and appreciate what you’ve done for the community immensely.

HeatingHelp.com · January 4

Let's start the new year off right and get along. Thanks!

delcrossv · January 4

Being a believer in "slower is better " I take the manufacturers minimum piping to be just that: minimum .

If you have two supply tappings, I'd say use them.

@ethicalpaul , sure steam is compressible, but per Mr. Bernoulli, velocity goes up which is not what you want in near boiler piping imho. Sure, there are diminishing returns, but going up a size or two isn't there yet.

ethicalpaul · January 4

well my Peerless manual does not use the word “minimum” at all related to the size and number of supply piping. It says what to use.

ChrisJ · January 5

https://forum.heatinghelp.com/discussion/comment/1832008#Comment_1832008

It's considered perfectly acceptable to use the manufacturers recommendation on an EG-75 simply because you can't go any bigger but following the same exact engineering on an EG-30 and all of a sudden it's"minimum" and not good enough.

That's the part I don't understand.

Intplm. · January 5

Decades ago when I first discovered Dans books I remember seeing a picture like this and or other similar pics. The discussions with this type of picture mentioned that the two upper steam chambers helped to allow for the driest steam possible. See the two upper steam chambers.

With the shrinking of the modern day steam boiler, a near boiler piping set of directions evolved to help with providing the driest steam in a modern steam boiler possible. Look at the original post Fig.44, two pipe risers. The two pipe example, and it is an example, is considered a drier near boiler steam piping arrangement by many. And is considered by many to be the better install.

When I supervised a large crew and they started to second guess themselves, I reminded them that at the end of the day all you have is your reputation. Do the best job that you can and your good reputation will follow.

And when I replace an old steamer with a new one, I remind myself of my own quote and I remember this picture.

jesmed1 · January 5

I'm reading Dan's book The Lost Art of Steam Heating for the first time, and today I read the section headed "How Many Risers Do You Need?" (pg. 48)

The example he gives is of a new boiler that cracked right after install. The installers ignored the mfr's instructions to use two risers, and instead used only one.

The result was that the steam leaving through the single riser had double the velocity it would have in two risers. The excessive steam velocity created a pressure imbalance inside the boiler that tilted the waterline inside the boiler, sucking water up near the riser and exposing the crown in the rear, exposing the metal to the flame, cracking the boiler.

Obviously this is an extreme case, but it shows another reason why it's important to keep the steam velocity within acceptable limits by using the right number of risers and the correct sizing.

delcrossv · January 5

https://forum.heatinghelp.com/discussion/comment/1832039#Comment_1832039

Maybe I'm overthinking, but I don’t understand your question.

FWIW, the ol' JB5 has 2 6" supply taps. Whoever installed it many moons ago used one tap, and immediately reduced it to 4" with a reducing ell up to the header. Wrong in theory, but the huge 8x16 steam chest saves the day.

They just don't build them like that anymore.

Mark N · January 5

@AndythePlumber, back to your original post. The cross sectional area of the single 6” pipe is actually larger than the two 4” pipes specified for the LGB-14. In theory the velocity of the steam leaving the LGB-14 with a single 6” riser would be lower than using the two 4” risers. Maybe two is specified because of the number of sections, but using two 5” would result in lower steam velocity.

Jamie Hall · January 5

A thought brought on by a comment of @ethicalpaul 's. Saturated steam (what we are playing with) is weird stuff. Yes it is compressible, but unhappily for our fun and games it doesn't behave quite as Bernoulli would have it. The problem is that it is, by definition, a vapour at its condensing temperature at the pressure it is at. Now… when you run it though a constriction (say an orifice or a venturi — or a reduced port valve) it does speed up and the pressure does drop, as you would expect. But… when it comes out the other side, it slows down and the temperature tries to drop and the pressure rises again… and at least some of it will condense; the heat from that condensation maintains the temperature and pressure. Not a problem in a radiator — in fact, that's exactly what you want it to do. But it is a problem in pipe work, and is why reduced port valves should never be used (among other things).

I'm not totally convinced that the apparent extra carry over from a one pipe riser setup compared with a two pipe riser setup is carry over. I suspect at least some of it may be from this expansion characteristic. I also suspect (a new idea this morning!!!) that there may be some benefit to ensuring that the cross section area of a header is at least as large as, if not larger than, the cross section area of all steam mains attached… hmm… have to think about that one.

ethicalpaul · January 5

thanks for your description of that @Jamie Hall

If anyone wants to see that behavior of the condensation occurring after a constriction (and just how extreme the constriction can be while still delivering dry steam), watch my video I linked above, it’s right here

the condensate doesn't get carried into header in my case, and based on how much I had to throttle the valve to get this to occur, it would have to be a dramatically undersized piping indeed to cause real trouble (I don't know, like less than 50% of the specified cross-section)

dabrakeman · January 7

I am attaching a table I made for information only. It is nothing but calculated steam riser and header velocities derived right out of the WM manual specs for various boilers including piping options from the manual if more than one configuration of risers is cited (i.e EG boilers). My green, black and red font is used only to highlight differences and not in any way intended to say the values in red are not acceptable but maybe just cases where consideration could be made for variation from the "minimum" recommended NBP sizes. Yes, the WM manuals do state these are "minimum" recommended. There are general trends here (also seen for the other boiler manufacturers) that higher steam calculated velocity is acceptable for bigger than smaller boilers. This may have to do with air space in the chamber and/or effects of larger piping in general on water carryover. Some things do stand out though as would be expected when a continuous range of steam EDR's is categorized into brackets of finite pipe sizing. Some cases though stand out more than others such as LGB8 vs 7,6 and 5 or 880 vs a 980.

Have one of these for Peerless 63, 64 and 211A series if anyone is interested.

WM Manual Recommended riser and header velocities.pdf

EdTheHeaterMan · January 7

I'm going for the bonus question.

The model designation LGB is used on Weil McLain's Large Gas Boiler.

ethicalpaul · January 7

The model designation LGB is used on Weil McLain's
Large Gas Boiler.

Which clearly went on to inspire the naming of the BFG firearm in the game "Doom" 😅

Please click the "off topic" button below since the site won't let me click it on my own post

Mad Dog_2 · January 8

On brand spanking new installations, if there are two possible tappings ,or more like the Steamax 500 (4- 2" tappings) I'm using them. Unless it's impractical to use two, then I will use one and blow up a size or two.

When coming in after the fact, often years later, I'm not going to destroy the boiler jacket and risk disturbing everything by trying to remove a buried 2"-4" Plug. Here, I will reuse the one tapping and blow up in size. Works great and dry steam wafting out. Mad Dog

EdTheHeaterMan · January 8

Look at @ethicalpaul being a comedian!!! 🤣🤣🤣🤣🤣

2 risers compared to 1 on steam boiler?

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