Steam boiler cutaway?

Precaud

Does anyone have a link to a good cutaway view of a "typical" gas-fired residential steam boiler? I'd like to get a better sense of the innards. All google returns is large industrial ones.

Thanks.

ChrisJ

Here ya go.

mattmia2

There are a lot of different designs. your 1950's boiler is probably closer to a commercial boiler than to a modern conventional domestic boiler.

mattmia2

here's one:
https://forum.heatinghelp.com/discussion/162701/weil-mclain-gas-fried-water-boiler-rusted-out-in-3-years

there are a lot of others if you search here

ChrisJ

mattmia2 said:

There are a lot of different designs. your 1950's boiler is probably closer to a commercial boiler than to a modern conventional domestic boiler.

I don't think I've ever seen a firetube or a water tube residential boiler?

The picture I posted, while it was a joke, was actually still pretty accurate, at least for a pin type boiler which most are. Essentially a cast iron pot of water sitting above a burner with vertical passages to allow the heat/flue gasses to pass through it.



A 3 pass, which is far better has some air passages going back and forth that allow the heat to pass through the water 3 times before exiting and the flame source is surrounded by water.

The "steam chest" you hear some speak of is just a large space at the top with no water. A clam area to allow water to fall back, and to keep the steam from dragging water with it out into the system.

Precaud

mattmia2 said:

here's one:
https://forum.heatinghelp.com/discussion/162701/weil-mclain-gas-fried-water-boiler-rusted-out-in-3-years

Interesting. So the "sections" of the boiler are the two clamshell pieces shown at the top, held together how? Looks like water inlet at the upper-left of the castings, steam outlet at bottom-right. And the section inlets are joined together with nipples? The holes upper-right and lower-left appear to be structural; the sections are hung vertical from these?

If correct, this looks like a leak-prone setup between the castings for each section.

HVACNUT

You can download any I&O manual and look at the exploded diagrams to get a sense.

I think Weil McLain has a demo on wheels with glass piping so you can see what's going on inside.

Anyone know of this?

retiredguy

Most of the boilers that google showed are just residential boilers up-sized or enlarged to become commercial boilers. Residential boilers can be water tube or fire tube, Atmospheric as @Mattmia2 showed, or multiple pass cast iron or steel boilers that are fired with a power burner. So what is a "typical" gas fired residential steam boiler? It depends on what you call typical.

ChrisJ

retiredguy said:

Most of the boilers that google showed are just residential boilers up-sized or enlarged to become commercial boilers. Residential boilers can be water tube or fire tube, Atmospheric as @Mattmia2 showed, or multiple pass cast iron or steel boilers that are fired with a power burner. So what is a "typical" gas fired residential steam boiler? It depends on what you call typical.

Can you show us a residential water or fire tube steam boiler?
I've never seen one, so I'm curious who had made one?

To me, a typical gas fired residential steam boiler is an atmospheric pin type cast iron boiler. I've yet to see anything different. Aside from wet based oil boilers that have a gas gun installed in them and even then, it's certainly not a fire tube or water tube boiler.

Jamie Hall

@Precaud -- the sections of a Weil-McClain -- at least the 80 series with which I am quite familiar -- are sealed to each other with O-rings of square cross section, which are seated in match machined grooves around the passages between sections. If they are properly installed -- that is correctly seated in the grooves (which takes careful, but not extraordinary, workmanship) and if the tie rods between sections are properly torqued (which does not mean finding the gorilla in your crew on a three foot wrench) they seal well and rarely leak. If either of the two conditions above are not met you will have a problem.

mattmia2

@ChrisJ someone posted an older, very sooted up water tube residential boiler a month or 2 ago.

EDIT: That was a hot water boiler. Residential steam boilers I think tend to be various sectional cast iron designs.

ScottSecor

@ChrisJ I believe Columbia still makes steel residential boilers. We have worked on a few of these and others with similar design. Almost all of the ones I've seen were oil fired and vertical tubes. Not sure I've ever worked on a small residential horizontal fire-tube boiler.

STEVEusaPA

HVACNUT said:

You can download any I&O manual and look at the exploded diagrams to get a sense.



I think Weil McLain has a demo on wheels with glass piping so you can see what's going on inside.



Anyone know of this?

Yeah they bring it to the trade shows. Also the PPA in Harrisburg has one set up at their training facility-just clear plastic piping to see how steam & condensate move thru the header/piping.

EBEBRATT-Ed

You can find the Weil McLain glass piped boiler video on u tube

mikeg2015

As mentioned above, and in diagrams, cast iron atmospheric boilers have multiple sections, similar to a radiator. Like a radiator, they are onlly connected to each other at single points.

In most, the sections connect at the bottom across the return, and at the top at the “steam chest”. Each section has a cavity filled with water. The burner side has “pins”... sort of like little fingers, and they almost touch, to absorb heat and tranfer it to the water. If it’s a hot water boiler, the pump circulates the water through the section upward. Cast irons boiler can operate with only gravity flow or no flow without damage.

IN steam, most evaporation occurs at or near the surface where water pressure is lowest (pressure increases with depth and boiling point therefore increases slightly at the bottom of the sections than at the top. Water will also boils where it contacts the hot metal.

Overall, they are very similar to a cast iron radiator.

mikeg2015

Here’s my old HB Smith G300 after I dismantled it.

Precaud

EBEBRATT-Ed said:

You can find the Weil McLain glass piped boiler video on u tube

That's very cool - thanks. Good demo of near boiler piping and pressure.

dennis53

Capitol Black Top 3-pass boiler, c. 1930

ch4man

ao smith burkay, fire tube boiler

mattmia2

does it have more than one tube?

Gordo

See who shows up at the end of this video...
https://www.youtube.com/watch?v=J5mzrLlIHbY

mattmia2

Should post that every time someone posts a picture of their near boiler piping with the boiler just piped directly in to the main and wondering why water is spewing everywhere.

retiredguy

In defense of my statement that steam boilers come in a variety of designs, I should mention that in addition to working mostly on large boiler systems that I had the occasion to work on a few mansions of the super rich and I considered their installations residential. Most of the literature that I had on the boiler types I was introduced to are no longer in my library, however my statement was correct. for example, H B Smith made a 3 pass cast iron boiler fired with nat gas or oil that were installed in a residence. Parker Boiler made and still makes a water tube boiler (bent tube) that can be steam or hot water in sizes starting at 1.5 HP (50,215 BTU input). Lattner makes a vertical tube boiler starting at the same input as the Parker boiler. There have been others that are no longer in production that I saw in my 40+ years of boilers service. I am sorry if I offended anyone with my statement but as some of the writings show there were many boiler designs that guys see from time to time that are in the "waste bin" of time. Here's one for the books, many years ago, I saw a multi-unit apartment building that had a side arm heater, one per apartment, like those used on domestic hat water heaters of yesterday, heating each apartment. Each had a small pump and finned tube emitters

ChrisJ

retiredguy said:

In defense of my statement that steam boilers come in a variety of designs, I should mention that in addition to working mostly on large boiler systems that I had the occasion to work on a few mansions of the super rich and I considered their installations residential. Most of the literature that I had on the boiler types I was introduced to are no longer in my library, however my statement was correct. for example, H B Smith made a 3 pass cast iron boiler fired with nat gas or oil that were installed in a residence. Parker Boiler made and still makes a water tube boiler (bent tube) that can be steam or hot water in sizes starting at 1.5 HP (50,215 BTU input). Lattner makes a vertical tube boiler starting at the same input as the Parker boiler. There have been others that are no longer in production that I saw in my 40+ years of boilers service. I am sorry if I offended anyone with my statement but as some of the writings show there were many boiler designs that guys see from time to time that are in the "waste bin" of time. Here's one for the books, many years ago, I saw a multi-unit apartment building that had a side arm heater, one per apartment, like those used on domestic hat water heaters of yesterday, heating each apartment. Each had a small pump and finned tube emitters

You absolutely didn't offend anyone.

Hap_Hazzard

ChrisJ said:

You absolutely didn't offend anyone.

Right. This isn't twitter.

Precaud

Well it turns out I had the answer to my question sitting in my computer, thanks to a catalog scan posted by @PMJ a couple months ago. It has a cutaway of my boiler:



This looks quite different from the WM castings in the link posted earlier by @mattmia2 .

Each cast section (there are 7) of this boiler appears to have four discrete horizontal tubes, the topmost tube is larger (the steam chest?). The water line coincides with the top of three smaller tubes in the middle sections. I'm guessing the tubes of each section are interconnected via runners or channels on the ends, maybe also in the middle, like a radiator turned sideways. The frontmost section is a different casting. The tubes are larger (taller) to accomodate the drain spigot at the bottom and steam outlet at the top. It would also be used for the rear section, to accomodate the water feed and return at the bottom, and its top steam outlet.

This explains to me why, when I add water, it takes some time to see the level actually change in the gauge glass. It has to propogate through quite a maze to get there. And why, when draining the boiler, it doesn't "gush" out of the opened drain cock.

This also looks like it would be an efficient and effective geometry for separating water and steam before it reaches the outlet. At "idle", there is no water in the large top "steam" channel of each section.

Thoughts?

PMJ

Obviously Bryant made a fine boiler. Better than anything you can get today for all in annual cost to the owner(s).

mattmia2

Shows you what the original gas valve looked like too.

ChrisJ

mattmia2 said:

Shows you what the original gas valve looked like too.

The hot air furnace in the house I grew up in had a similar gas valve and regulator. The pilot light was plumbed completely separate with it's own shutoff valve, but no thermocouple.

It worked without being touched for 46 years before the valve failed and was replaced with a combination gas valve and regulator. Ok That's a lie, I think my dad cleaned the pilot once and replaced the thermocouple.

The original valve had a very distinct clink sound when it turned on.

Precaud

mattmia2 said:

Shows you what the original gas valve looked like too.

That being the round thing in the left-front corner?

ChrisJ

Precaud said:

mattmia2 said:

Shows you what the original gas valve looked like too.

That being the round thing in the left-front corner?

No, that's a pressure regulator. Next is the gas valve.

mattmia2

@ChrisJ that is a result of a rule change sometime in the 60's. That rule change required total shut off controls that would turn off the gas to the pilot if it went out. Before that the pilot burner was not required to shut off if the pilot went out, just to prevent the main burner from turning on.

Precaud

Ah, ok, I get it. Valve and regulator were separate units back then.

mattmia2

There were also different valve designs.

Usually the manual main shutoff valve had taps in it before the valve to connect the pilot burner and shutoff valve.

retiredguy

Oh yes, just sitting at my desk and remembering the old style furnaces and boilers equipped with gas valves, pilot combinations, and controls of yesterday's simplier life that are no longer made since the government stuck their nose into the pot of stew. Back then the furnaces and boilers would usually last a life-time if they were serviced on a regular basis. They were big and bulky and easy to access. General Controls and Detroit even made "self contained" modulating gas valves for furnaces and boilers. Just sitting here and dreaming of yesterday.

mattmia2

there was some detroit company that made gas valves?