May be a stupid question but here it goes.. how come old steam boilers are so large?

tomsloancamp

I am curious about the reason old Residental steam boilers are much larger then current models? Why the need to hold that much water?

JUGHNE

Larger "steam chest" above the water line would give you drier steam. Now the near boiler piping must dry out the steam.
This is the cause of a lot of problems with new boilers just installed with the "cut and slide" method.

Heavy, more iron/steel was thicker and lasted longer.
But took longer to pass heat thru. Thinner iron is quicker for heat transfer. Government requirements caused this to squeeze a little more efficiency out of the boilers......and possibly was an opportunity to build a more economical (could we say profitable)
unit. Some use the term "race to the bottom".....IMO

retiredguy

One more item to add to @JUGHNE post; A lot of the older boilers could have been fired with coal. If that is the case the firebox needs to be much larger to get the heat out of the burning coal. Depending on the boiler, a unit fired with coal could be fired with nat gas or fuel oil at a much greater rate than when firing coal. I always preferred a boiler with a large steam chest to produce dry steam than to rely on a contractor do build a steam header to produce the same dry steam. A lot of the newer contractors have no idea how to pipe the "near boiler piping", or just do not care.

JoeyG_2

"Sad but true" -Metallica

-Joey G

clammy

On that race to the bottom I include what I think is to much of a minimum header pipe sizing in the manuals and there near boiler piping kits ? Well they seem under sized to me and I never would think of any header piping on tiny boiler smaller then Full riser and 3 inch header but that’s me add a 2 equializer and your done .i really can t figure weather it’s just lack of knowledge or lack of giving a crap or it s how they conduct the business like a mill grinder it take complaints until the HO shouts uncle and fires them to try n get someone else to only later come here and find the truth about near boiler piping and steam system . I think anyone who works on older low pressure steam heating system should always pay homage to Mr Holahan for all the vast knowledge that he s put together for us and made available also that he s put it all in plain English that guys that are not rocket scientist can access . Peace and good luck clammy

SeanBeans

Another way to look at this question is: why are the new steam boilers so small?

There are now smaller because of the newer guidelines for efficiency. Back then they weren’t forced to make a 80%+ boiler.

But they were forced to prove they could produce dry steam. So the bigger the steam chest the drier the steam.


From the perspective of Sean... dundundun

tomsloancamp

I’m not sure what I should be looking for in a header compared to what I have. I should probably invest in one of Dan’s books.

ethicalpaul

tomsloancamp said:

I’m not sure what I should be looking for in a header compared to what I have. I should probably invest in one of Dan’s books.

Definitely do that, and while you are waiting for it to arrive, look at the pdf of the installation manual for your boiler to see the bare minimum.

mikeg2015

One hte positive, the smaller boiler heat up faster and in mild weather, more heat goes into the conditioned space rather than the basement. WHen there’s an indirect on a hot water loop, it’s even better. It recovers faster. Less overall surface externally gives up less heat. Lower water volume is less water to heat up. As well.

tomsloancamp

Thanks everyone! New boiler in and old one out. Now I get to see the difference. What I can’t figure out is why the concrete foundation was removed (or never put in) right below the old boiler. The house was built in the 1920’s. I don’t know if that boiler was original to the house. It definitely was older Arcoliner( I included pics.)

gfrbrookline

There is a possibility that the concrete floor was a added after the boiler was originally installed. Make sure the new boiler maintains the same water level as the old one so you don't have issues with your piping and hammering. Measure it before they remove the old boiler so you can verify.

ChrisJ

> @gfrbrookline said:
> There is a possibility that the concrete floor was a added after the boiler was originally installed. Make sure the new boiler maintains the same water level as the old one so you don't have issues with your piping and hammering. Measure it before they remove the old boiler so you can verify.

It would be much better to inspect the piping to see if there's any reason to put the new boiler a foot or two in the air first.

Mike_Sheppard

Because they were less efficient.

ChrisJ

My house had two Burnham V8's rott out in 8 years before I bought it and yet our neighbor had a 1920s Redflash 3 pass boiler going through a ton of makeup water for years due to leaky vents, valve stems etc.

The Redflash didn't mind at all. I don't know how much it held, but it seemed to be a good 40 gallons. It was a converted coal boiler running on oil.

The older boilers may have been less efficient, but they sure seemed to last a lot longer.

retiredguy

My thoughts on why the new boilers are so much smaller than the old boilers is cost and how long they will last. The smaller new boiler would cost much less, be easier to install due to physical size and weight, and will not last as long as a well made American Standard Red Flash or Arcoliner. Geeze, If they last too long we won't be able to sell them a new one as soon as the warranty runs out. I wrote in a previous post that in the mid 1970's, the company I worked for sent me to the H B Smith factory in Westfield, Mass. to see how their boilers were made. During my time there I was escorted to their testing area where they were experimenting with these very small cubes (boilers) to see how small they could make a functioning boiler. They were trying different ideas such as size, portability, efficiency. It looked like a bunch of kids with an "erector" set trying to make the impossible. I thought it was a waste of time which it probably was. The new "JUNK" is probably the result of some of their experiments.

PMJ

"The older boilers may have been less efficient, but they sure seemed to last a lot longer."

To me this really means that the older boiler is actually the more efficient one. It sure gets a lot more heat produced per dollar spent when you add up all the dollars compared to boilers made today. That is the only efficiency I care about.

Jamie Hall

Cedric's predecessor by a couple of generations was an H.B. Smith -- which was huge. And had a separate steam drum on top of it (which is still in use -- a rather complicated and strange looking piping arrangement, but works beautifully). Result -- insanely dry stearm Efficiency? Um... not so much. It was fired at 5 gallons per hour and could just barely keep up on really cold days. Cedric manages very nicely, thank you, at 2.75.

ChrisJ

> @Jamie Hall said:
> Cedric's predecessor by a couple of generations was an H.B. Smith -- which was huge. And had a separate steam drum on top of it (which is still in use -- a rather complicated and strange looking piping arrangement, but works beautifully). Result -- insanely dry stearm Efficiency? Um... not so much. It was fired at 5 gallons per hour and could just barely keep up on really cold days. Cedric manages very nicely, thank you, at 2.75.

But does the fuel being saved outweigh the cost of replacing it every 10-20 years?

As far as dry steam, even without a steam drum my wet return is 2ppm TDS. The water coming back front the radiators is virtually distilled water.

Jamie Hall

Good question on the fuel saved vs. replacement costs... haven't calculated that! And we kept the steam drum as much because in some ways it was simpler... and besides, Charles wanted to do something a little fancy!

tomsloancamp

Would there be any reason to leave a hole in the foundation below the boiler in case of leakage/failure from the boiler? Possible concern the heat produced by the boiler would crack the foundation? Just wondering.....

ethicalpaul

It was probably due to issues raised by @gfrbrookline above-- water line/"A" dimension stuff to ensure proper operation.

See https://www.usboiler.net/tips-successful-steam-boiler-replacement.html

JUGHNE

I am on the board of our small 1914 museum.
All piping and boiler were removed over 50 years ago.
From ciphering the size and location of the holes for piping and a few remaining pipe hangers, my best guess is that it was coal fired hot water gravity.

There is a dirt rectangle where the boiler sat. Poured floor all around it. This building had pads poured for 8 x 8 wood posts and then the floor poured later. The wood posts going below grade were a great termite path BTW. That is now corrected.
The pad may have been poured for the boiler below grade also and the floor poured around the boiler. There is no evidence of the lower pad though.

Gilmorrie

It's not just steam boilers - newer hot-water boilers are also much smaller, physically, than older ones. 50+ years ago, boiler nameplates listed the heat transfer area, sq ft. For a fire-tube boiler, for example, the heat transfer area is just the total surface area of the tubes. A figure of merit was the Btu/hr divided by the heat transfer area - the smaller the number, the better, so larger boilers were perceived as more efficient because they could wring more heat out of the flue gas as well as being longer lasting. Nowadays, a boiler's heat transfer area is seldom if ever mentioned.

tomsloancamp

Any suggestions on a book I should start with?

Jamie Hall

Sure -- and they're available on this site, in the store, at a fair price. "We Got Steam Heat" -- basic, but not a bad place to start. Then "The Lost Art of Steam Heating". Not basic, but if you absorb everything in it, you'll be a pretty good steam man...