Recent DeKnuckleheading

JStar

This steam boiler was installed about two years ago by another contractor. Homeowner was experiencing bad water hammer and uneven heating. The boiler is oversized by about 60,000 BTUH. We installed two 3" boiler risers and a 4" drop header. We also upgraded the main vents on three mains with GORTON #2 vents, and installed a new Vaporstat set for < 8oz.

KC_Jones

Fantastic work!

JStar

Hatterasguy said:

Since the boiler is unchanged, and only the near boiler piping and vents were properly done, would it be possible to stay in touch with this homeowner and get a back to back comparison on the gas utilization last year with the gas utilization for the 2015-2016 season?

We speak eloquently on how important the near boiler piping is to performance, and yet, nobody has posted actual data. The reason being is that the boiler is usually replaced at the same time so it's not generally available.

Personally, I'm dead curious to know exactly what properly sized near boiler piping with the drop header and sufficient venting offers as a percentage of fuel consumed.

I think about this a lot. We try to encourage people to collect their utility bills and send them over. About 5% actually do. Based on heresay only, we see people saving SOMETHING on their bills after we re-pipe a boiler or upgrade a system. Usually, re-piping is done to eliminate noise or copper corrosion first, and fuel savings is a bonus.

MarkS

One man's experience: When we put the Midco LNB burner in back in 2013, JStar also replaced all the near boiler piping that was knuckleheaded by the original installers with a proper 3" drop header and multiple takeoffs to the mains.

I upgraded the main venting when the boiler went in, so the only change was the near-boiler piping, assuming the Midco fires at a constant rate. I actually ran some tests with the Midco firing at the same rate as the old oil burner and compared them to the original system, and found the time to get steam to the mains from a cold start was cut by about 3 minutes and from a warm start by 30 secs to a minute or so. Steam time to end-of-main wasn't affected much because the proper venting was already in place.

Half a minute doesn't sound like much, but with 3000 firings over the last heating season (on a 30 minute cycle), it adds up. In this case, at least a day's worth of fuel saved.

jumper

Energy savings depend on how folks deal with unbalanced systems (improved near boiler work improves system balance).
If people open windows in overheated rooms that obviously wastes energy. If they resort to covering radiator or shutting it off then maybe gas consumption doesn't improve that much.

MarkS

You'd need careful rigorous study on a test bed akin to what the University of Illinois Engineering Experiment Station had back in the 20's and 30's to get that answer. Anything else, including my own experiments and results, is purely anecdotal.

JStar

For the cost of 2 extra fittings and 2 extra nipples, it's worth trusting the rhetoric even if it turns out to be hyperbolic. One of these days, I'm going to make a vertical header. Maybe when I convert my own house to steam.

SWEI

JStar said:

One of these days, I'm going to make a vertical header. Maybe when I convert my own house to steam.

OK, I think have a picture in my head. Interesting...

JStar

Hatterasguy said:

JStar said:

For the cost of 2 extra fittings and 2 extra nipples, it's worth trusting the rhetoric even if it turns out to be hyperbolic. One of these days, I'm going to make a vertical header. Maybe when I convert my own house to steam.

I don't think the drop is the real issue.

The question is the difference in fuel consumption between a "cheap" 2" header (very common) versus the 3" or 4" headers utilized (150 to 300 K systems) to slow the steam down before it can get to the mains.

I always figure that a 2" pipe full of steam and condensate is not really a 2" pipe. If it's saturated with steam and puddled with condensate, it will effectively act smaller. But how much smaller? I can only guess. By oversizing headers, we're really choosing a "net pipe size" that we know will handle both the total BTUH's worth of steam and the action of condensation and boiler carry-over. I think of it as the Stack Loss or Jacket Loss of the header. So, for me, it may not always be justified in fuel savings, but it will always deliver the appropriate amount of steam in the required time. Comfort does not necessarily require a positive ROI.

As for real, hard numbers on fuel consumption for an undersized/oversized header....I'm personally not willing to test it on my customers.

vaporvac

Yet another plug for modulating or staged firing.

jonny88

So what do you think.This is very interesting as you measured to radiation, vented 100% properly.So you do everything by the book drop header etc and still 50 % oversized.You are testing here with data to prove.Do you size the conventional way on half the output.I know you are very thorough and would really like to hear the steam experts chime in here.Maybe bring it up on another thread as I feel it is a very important ? and one where I am looking forward to see some input.Great job.

jonny88

Again its going back to the fundamentals on boiler sizing.It is beyond me that this is even a ? All the research into steam and you are saying we are oversizing by 50%.
More than willing to come to your job and experiment if you are interested.
Love to help.

jonny88

But importantly you want to keep venting away from tennants so varivents are not an option?

jumper

Unless you have multiple boilers or staged burners you are oversized most of the time.Need ability to keep building habitable when it's -10° outside. So when it's 50°?

STEAM DOCTOR

Beautiful job as usual. Is this a Williamson? I wasn't aware that they ship them with the thermoflo tag.

ChrisJ

How would you build a vertical header? basically pull your mains off of the equalizer and not have any horizontal section other than what you need to clear the boiler?

Has anyone done this?

j a_2

Very nice job...love the use of cast iron fittings......I have not but has anyone ever use the formula to compute the steam velocity at different joints at the near boiler piping? Clearly doubling the number of risers cuts it in half at boiler tapping exit...Per the lost art...I'll give it ago and see what I come up with....Average homeowner with steam especially the non original owners can't understand why the entire radiator does not get hot all the way across... Even though the tstat is satisfied... Another subject t stat locations. Jstar you sir do proud to the steam guys, and your work helps rase the bar on quality installs....A homeowner with issues coming here looking for help and has the savy to compare his recent chop job to yours will cleary see his answer to his issues...

ChrisJ

Not entirely true. The purpose of twin risers is to slow the steam leaving the boiler which means less water is pulled with it. Having two also keeps the water level from being pulled to one side as well which again keeps more water from leaving.

j a_2

Chris, I agree, and the first sign is the fluxuating water line and the dropping of the water level...But also the bigger the header the better.... I would love to know via a computation what the velocities are up to the main...

j a_2

I'll mess around with it as I have the dead man's work book and old dead man school on video from Dan
...We as steam guys and the techinal input from the savey homeowners here that post are very helpful, all together its makes for a great site....

JStar

****Header Size per Maximum BTUH Output****
(Based on Velocity of 15 ft/sec. to 20 ft/sec. @ 1psi pressure)
2" Header = 48,384 - 64,512
2.5" Header = 68,832 - 91,776
3" Header = 106,416 - 141,888
4" Header = 183,312 - 244,416
5" Header = 287,856 - 383,808
6" Header = 416,016 - 544,688

I'll choose the size and amount of boiler risers depending on the particular boiler manufacturer. I'll usually take my header rating divided by 2 to get the size of two risers. For some 3" headers, only one 3" riser is necessary.

JStar

Hatterasguy said:

So, Joe............did you EVER use a 2" header..............in your entire career?

When I first started, yes. And sometimes to keep a customer's budget within a reasonable range. My first choice is always 3" as a minimum, though.

JStar

I agree. A 2" header just looks wrong to me now. That size only belongs on the smallest of boiler sizes.

From the calculations I've done, most/every manufacturer's reccomendations for pipe sizes fall in the 75 to 100 ft/sec range. Scary stuff!

I don't believe that the length between risers and mains will make much difference, other than smoothing out the steam travel pattern. But, a large header will have the same effect without the length requirement. As steam enters the header, it will expand to take up more volume, slow down, and mellow out. I dream about that glass header.

j a_2

Two 2 in. risers at 24 in. into a dropped header to a 2 inch main is perfectly acceptable... Any thing over that is great but not totally necessary... no argument from me about that.

j a_2

JStar said:

Hatterasguy said:

So, Joe............did you EVER use a 2" header..............in your entire career?

When I first started, yes. And sometimes to keep a customer's budget within a reasonable range. My first choice is always 3" as a minimum, though.

If you truly believe in a 3 in. header and that is your standard...Why would you install something less....just to meet the budget, of a homeowner looking for a cheap bid...

JStar

j a said:

JStar said:

Hatterasguy said:

So, Joe............did you EVER use a 2" header..............in your entire career?

When I first started, yes. And sometimes to keep a customer's budget within a reasonable range. My first choice is always 3" as a minimum, though.

If you truly believe in a 3 in. header and that is your standard...Why would you install something less....just to meet the budget, of a homeowner looking for a cheap bid...

Because I always do what's best AND appropriate for my customers. There are a lot of things that I suggest doing to a sysytem, but if somebody can't afford those upgrades, or the ROI isn't there, then no work gets done at all. I treat every system as if it were my own, but I understand that I'm not the one who's paying for the work, and the customer makes the final decision.

I tell people what the manufacturer's minimum requirements are, and how dissappointing those standards are as well. But, sometimes, when the budget is tight, a few items get left out (header size, burner staging, vaporstat, etc.).

Maybe I wasn't clear that I'll never use a 2" header on any boiler over 75,000 BTUH input; only the smallest sized systems.

j a_2

Good answer jstar we all do what's best for all involved.... I am sure that you as I never would have done a job we did not agree with.......There was always another job somewhere..36 years installing boilers gave me a lot of experience...Using my head first then my hands second always worked pretty well.

JStar

Hatterasguy said:

ChrisJ said:

Not entirely true. The purpose of twin risers is to slow the steam leaving the boiler which means less water is pulled with it. Having two also keeps the water level from being pulled to one side as well which again keeps more water from leaving.

When that steam doubles in velocity in the header after leaving the two beautiful risers that you have carefully installed to slow down the steam............what is the result?

That's assuming that the velocity increases in the header. If the risers are sized with the same charts as the header, the velocity will be the same leaving the boiler and the header.

ChrisJ

I suspect even if you did two 3 inch risers into a 2 inch header there would be a benefit over a single 2 inch riser. It would still pull far less water out of the boiler.

Try viewing the risers as completely separate from the header. The job of the risers is to keep the water in the boiler in the first place. The job of the header is to remove any that escaped.

Danny Scully

There is a benefit in using both riser tapings on any given steam boiler, regardless of header size; it's referenced in The Lost Art. The benefit is that there is even steam delivery off the surface of the water. If you only use one riser taping, the water level will actually pull towards that single riser taping, which on modern boilers isn't in the center of the boiler, it's to one side or the other. You can actually notice it in the gauge glass.

JStar

There is definitely a balance-curve for the amount and size of risers. I would never use smaller than 2", and I would also never increase the riser size if the boiler tapping is already maxxed out; it makes no sense to use a 3" riser on a 2" tapping (assuming that the header is properly sized).

Who wants to try!?

ChrisJ

JStar said:

There is definitely a balance-curve for the amount and size of risers. I would never use smaller than 2", and I would also never increase the riser size if the boiler tapping is already maxxed out; it makes no sense to use a 3" riser on a 2" tapping (assuming that the header is properly sized).

Who wants to try!?

I wouldn't try that but I'd be curious in the performance of two 3" risers in 3" tappings feeding a smaller header. It'd have to be piped in glass though and compared to one with a larger header.

ChrisJ

With risers, the higher the better within reason. I see no reason not to go 35-40 inches if you can. Mine ended up two 12" nipples + a union above my boiler because that's what I could easily get my hands on and I couldn't go much higher.

j a_2

It is not an argument, is a professional discussion... And all the more input is best for all....I for one listen. To all

JStar

Well, here's a little bit of a dirty secret. On most jobs, we're severely limited in the amount of space that can be used for the boiler piping. I would love to have 10ft of space around the perimeter of every boiler, but that just doesn't happen. And systems with three or more mains, fuggeddabouddit. To compensate for the immediate compromise, I'll make my risers as tall as possible, sometimes 24-36"+ above the top of the boiler, and size the header according to my charts. The last riser and first main are usually connected with the distance of a close nipple. Our systems run like a Swiss train.

I've come to put all of my faith in header sizing and riser height. All other factors account for slightly less benefit.

JStar

With the right size header, I don't even care how much water is really in there. The "oversized" header is an accumulator of sorts to allow condensate to drop to the bottom, and steam to pass freely on top. Plus, water is always sitting inside of the header fittings, causing steam to condense and produce even more water.

I wish there was a video of a smoke-test inside of steam piping.

gerry gill

Good looking job Joe! as always.

j a_2

As some seem concerned about, the cost difference between a 2,3,or 4 in. header is very very little...So hoping that is not the issue...Its about the confidence you have in your own work....And about the comfort of the home owner...There is well no cost difference with the velocities of the steam when your talking within the 10 percent difference.... The discussion now is about the thecnical end, and rest assured there are very few if any common homeowners that could care less about steam velocity . they care about safety and comfort....

ChrisJ

Woah wait now.

The cost difference between 2,3 and 4" is very little!?

I can assure you that is very inaccurate. If it was true, I would have two 3" risers into a 4" header. The bank couldn't tolerate such abuse when I piped the boiler.

2" fittings are cheap, real cheap. 3" fittings are very expensive. 4" fittings are painful.

Just did a quick check and 3" cast iron tees are 5 times the cost of 2" and 4" are 9 times the cost. Ells are similar.

j a_2

When I spoke of safety and comfort, the safety comment was to do about gas, venting, and make up air, not about steam safety....But that to is important.... About pricing, if u go up with 2 2 in. risers drop down to a header and upsize from there your talking about a couple of fittings, in the scheme of things that to me is not much....For some reason I feel I am constantly on the defence here....

gerry gill

Hey Joe- engineering wise you should have no issues with a vertical header (may need baffle plates) kind of like a steam separator or cyclone separator i would think. I've been wanting to experiment with a box header, since a square or rectangle would have greater internal area for separation than a round pipe. Was even thinking of a pyrex window in order to observe whats happening inside. Its good to be a steam psychopath