Skipping Header on low input, large tapping boilers

The Steam Whisperer

I know this sounds way out of bounds, but it should work when looking at the numbers. For a 3 inch tapping, you can get about 200,000 btu/hr input before the velocity is high enough for water carry over. So for those small boilers that are under that input, if you use 2 -3inch tappings to supply the system ( the common front main/ back main set up) you'll be at 1/2 the maximum carry over capacity, just like in the old days. I'd run those 3 inch supplies up at least a couple of feet just to be safe.

Steamhead

But what happens when the water gets dirty?

Somewhere on here is a video of the Weil-McLain boiler that is piped in Pyrex glass. The velocity is fairly high on that one, but when the boiler is running normally the piping keeps water from getting up to the header.

However, when they add a bit of vegetable oil to the water, it goes wild and fills the header.

Unfortunately, we don't work on perfect steam systems. The header might technically not be needed if the water is clean and the velocity is low, but just wait until the water gets dirty. It would be a guaranteed call-back.

JUGHNE

If the front/main--rear/main were not close to equal EDR and pipe friction, wouldn't one riser have more flow and perhaps draw the water to one side of the boiler creating problems?

In addition to what Steamhead pointed out.

Fred

Also, would you have to tie in an equalizer from each riser?

ChrisJ

@Steamhead Shouldn't you get a call back if the water is dirty anyway?

Dirty water must kill efficiency, no?

STEAM DOCTOR

@The Steam Whisperer (Formerly Boilerpro) .would certainly take lots of guts. Interesting and thought provoking idea.
@Fred. I would think that you only need one equalizer to keep water from backing out of the boiler. Also, I would think think that the equalizer can be smaller when it's only function is to equalize steam steam pressure. Normally, an equalizer is is both an equalizer and a drain pipe.

Fred

@STEAM DOCTOR so, you don't think that any water that does blow up into the risers needs a path to drain back into the boiler, other than just the direct path of dropping down from each riser into the path of the steam?

ChrisJ

Fred said:

@STEAM DOCTOR so, you don't think that any water that does blow up into the risers needs a path to drain back into the boiler, other than just the direct path of dropping down from each riser into the path of the steam?

The whole reason for this idea was that water won't be blowing up into the mains. Otherwise, you'd put a header with a drain.

Fred

ChrisJ said:

Fred said:

@STEAM DOCTOR so, you don't think that any water that does blow up into the risers needs a path to drain back into the boiler, other than just the direct path of dropping down from each riser into the path of the steam?

The whole reason for this idea was that water won't be blowing up into the mains. Otherwise, you'd put a header with a drain.

There are any number of reasons for water blowing up into the risers, including the discussion on dirty water. May only be a temporary situation but the impact of that situation should be considered.

ChrisJ

Sigh.

Who knows how all of those 80+ year old boilers worked flawlessly piped exactly as @The Steam Whisperer described.

Apparently it's impossible. What if the water gets dirty?

This is what I like about Dave, he thinks about what's going on and experiments. He doesn't walk around like a zombie repeating 33% because it's in a book.

Fred

ChrisJ said:

Sigh.

Who knows how all of those 80+ year old boilers worked flawlessly piped exactly as @The Steam Whisperer described.

Apparently it's impossible. What if the water gets dirty?

Not impossible but, fortunately @The Steam Whisperer (Formerly Boilerpro) posted looking for feedback and is probably interested in the questions/feedback. Also, all those old coal fired boilers were a different animal because they were coal fired. There are boiler today that don't have headers but we certainly don't know how they perform other than the HO saying it heats fine.
Allow people to participate in a discussion without the sarcasm. It's not productive.

ChrisJ

@Fred
Our neighbors have a converted coal boiler running an oil burner. No header, no equalizer. It works fine even at 2 PSI. Hmm?


The other day I'm on here reading comments about oversizing boilers for radiant being bad, cycling destroys boilers quick and kills efficiency. Can't be tolerated!

But not on steam, no, those boilers follow different laws because the book said you need to be 33% oversized.

Dave questioned that and found it wasn't true.



Dave,

Steamhead

The reason those older boilers worked OK without headers is they had huge steam chests, which provided the space for the water and steam to separate.

Fred

@ChrisJ , like I said, avoid the sarcasm. It's not becoming and get over the piping and pick-up factor. 33% has also been proven to work. Heck, there are those like @PMJ who would tell you an over-sized boiler is an asset. Let's get back to the topic of this thread.

ChrisJ

Steamhead said:

The reason those older boilers worked OK without headers is they had huge steam chests, which provided the space for the water and steam to separate.

Understood.
But I think Dave's point is there won't be any water to separate if piped as he described.

There's only one real way to find out.

Fred, can we come replace your boiler? You have to buy the material and equipment.

The Steam Whisperer

It just makes me wonder, since nearly all the old monsters almost never had headers and worked well with piping in this velocity range. The steam chest is the wild card.

ChrisJ

The Steam Whisperer said:

It just makes me wonder, since nearly all the old monsters almost never had headers and worked well with piping in this velocity range. The steam chest is the wild card.

Did all of them actually have a steam chest and if so what is it? Is it just a bigger space above the water line or is it a separate compartment?


Having as little experience with different setups as I do, the only assumption I come to is the older boilers had huge 4" tappings. How many boilers now are piped with a single 2" riser? It's not surprising it sucks water out of it with the steam.

Two 4" tappings, both used on a 150,000 btu/h boiler means something, steam chest or not. That's what's in our neighbor's house and the risers go up a good 35-40 inches.

The Steam Whisperer

The steam chest is a big cavern where the steam bubbles pop off the top of the water. However, Steamhead's concern about oil on the water may change that a bit or alot, since the steam bubbles are no longer popping very easily and then the boiler may be filling with foam into the piping..... at least that's what the videos look like. But then just how high is that foam going to rise up into pipes that are really big. I suspect once the velocity is down, you just need to get the pipes tall enough to allow the foam to break up before it reaches the steam mains. I suspect this applies pretty much whether there is a header or not. That 24 inch dimension above the waterline before going into the header is probably a big part of that equation. Those bubbles are going to start popping under their own weight once they stack up high enough.

Maybe.....
Risers off the boiler just need to be high enough to allow the bubbles to break, while the velocity needs to be low enough somewhere before the steam mains to separate the water and steam and provide some way for the water to return to the boiler.

Alas, I am hoping sometime soon I can replace the hot water heat and get the steam system in my home and give this a try. I need to fire about 50,000 input to meet my heat loss, so large risers should be easy.

The Steam Whisperer

Jughne makes a really good observation that most people seem to ignore including some big manufacturers...the tipping water line. However, in this case most of these boilers are usually only piped single tapping anyway, so the water would even be less inclined to tilt if the load is split unequally between 2 risers.

EBEBRATT-Ed

Want to try it??? Pipe it with a header and put flanges in the header between both supply risers. Put a blank off (frying pan) between the two flanges. Lube the two gaskets and the frying pan with never seize. If it works....fine if it doesn't....pull the frying pan torch a hole in it and put it back in

EBEBRATT-Ed

Steam chest or not just remember the physical size of the older boilers versus the new (and yes I know they were also oversized).

There was a lot less activity going on in the old boilers same input slower boiling. look at a pan simmering on the stove versus a pan at full boil

gerry gill

Excellent point EBEBRATT-Ed:
Big pot of water - smaller flame albeit same btu

or i guess a good way to put it would be, water to flame size ratio