Replacement Boiler Size Question
Just wondering in case my good old 1962 U.S. National Gas Fired Boiler decides to go out.
It's currently rated at 127,000 BTU input, 97,000 BTU output.
I have a Cape Cod Home in Chicago.
My rooms are as listed……..
Radiators are the very old type before 1918 that did not have the "Cross Tube" on the top.
They were strictly "Steam".
All Radiators are 38" tall, 3 Column.
My bedroom upstairs is 5 Sections
Bathroom upstairs is 3 Sections
Spare bedroom upstairs is 4 Sections
1 Living Room Radiator is 8 Sections
1 Living Room Radiator is 4 Sections
Dining Room is 8 Sections
Kitchen is 5 Sections
I spent a little time looking on how to calculate for a new Steam Boiler.
All formulas come up with "5. 0 per Sq Ft. Per for a 3 Tube 38 Radiator".
When I add them all up, it something like 48,000 BTU Boiler Size.
It don't make sense.
Any Professionals out there to use my numbers and let me know if I'm Under or Overfired ?
I live in Chicago.
There is probably less than 1% of "These "Heating Pros" that actually know about Steam Heat….
Comments
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37 sections x 5 sq ft = 185 sq ft net steam EDR. This figure is printed right on the boiler rating plate and is how steam boilers are selected. The net rating includes a standard 33% addition for piping and pick up factor.
185 sq ft x 240 Btuh/ sq ft x 1.33 = 59,052 Btuh boiler output / 83% combustion efficiency = 71,146 Btuh boiler input rating.
Which puts you in the category of the smallest steam boilers made.Your boiler is 79% oversized for your system. Oversizing of steam boilers is extremely common. Most contractors do not take the time to measure the radiators and do the math.
—
Bburd
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Numbers look good, I have the exact same size radiators in my house.
When you get a replacement you want the smallest boiler made, and even that is too big. Do not let anyone convince you otherwise.
You're current boiler basically gives you a 118% pickup factor instead of the normal 33%
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Maybe a SteamMax 075 (169sqft) or a WM EG30 (186sqft).
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Thank you. That's my next decision. Burnham or WM. Seems to be the 2 most popular options. I know one thing, neither one will last as long as the one I had now since 1962. Mine sits on a narrow "Pad" about 8 inches high right now. Size and location of sight glass, and fill valve will be a factor also. I need it to be on the left side of the boiler for easy access if possible
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If you can keep your system pretty much leak free, keep the pH up over 8.5, manage your pressure and at least occasionally clean the gunk out there is no reason to believe these boilers might not give you 30+years. Nonetheless, here's to hoping your "good old 1962 U.S. National Gas Fired Boiler" keeps chugging along for you (although your monthly bill might come down a bit with the more properly sized boiler).
Send us a photo of the old boiler. We love pictures…
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2 Pictures for you. Looks as good as the day it was put in. Lol !
Actually I do keep it looking good, no sight glass leaks, I replaced that and the gaskets about 6 years ago. Pressuretorl is about 7 years old, drain cock replaced last summer, Gas Valve about 6 years ago.
Only 2 times I had to call someone out for things I didn't know. This time when I had a big "bang" and the flames were all over. Never was cleaned from the top. It was caked up with Soot. Probably building up for years. I cleaned the burners but never thought of doing a top-down wash. Looking at the bottom of the boiler it always looked clean.
On the side in the picture you see how the metal is discolored.
That was happening about 6 years ago. I wasn't sure how to replace my old gas valve that had a "Sigle" gas valve that had the very old pilot type that had a separate gas shut off. If the pilot blew out, gas still would come out for the pilot. I had to upgrade to the "Combination Valve". The guy put the gas valve in and I had to call him back. Boiler would go "Boom" when the burners kick on and flames would shoot out. His dumb self so called "Pro" lowered the gas valve pressure, never used a gauge to see if it was the 3.5 it's supposed to be, he lowered the gas pressure by "Guessing". Solved the problem —- Temporarily.
My complete blockage from Soot I just had cleaned was probably starting to be a problem then and I never thought of looking at the top to see if it was clean since the bottom was always clean.
2 weeks ago when it went out I called a guy and it was blocked. He cleaned the heck out of it with water, made a mess, but it runs perfect now.
The last few years I always had yellow flames, could never get them blue no matter how much I adjusted the air to the burners.
When the boiler would fire the last few years i would always hear a "Poof". Like I can hear it pretty good from my 1st floor.
Burners are blue now, and I can't hear anything.
So far it's running perfect.
No more "poof" and no more Flame Roll Out.
Poor thing was starving for air all these years due to the Soot building up.
Here in my 1962 (2 years older than me) Boiler.
And not leaking a drop water anywhere, and tank don't leak
leak anywhere.
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