Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Sizing steam system (with photos)

those are large-tube radiators, same as American Corto, National Aero, U.S. Capitol and others. H&C is probably Hart & Crouse, a long-gone manufacturer.

I bet those guys are sizing the new boiler by the size of the old one. That almost always results in an oversized boiler. Stick to your guns.

<A HREF="http://www.heatinghelp.com/getListed.cfm?id=367&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"</A>


  • Chris_105
    Chris_105 Member Posts: 4
    sizing new boiler (with photos)

    I had posted earlier without photos, but couldn't find my old post. Anyway...

    Replacing this old single pipe steam boiler with a new Burnham MegaSteam. House was built in 1938, roughly 1500 square feet. I have determined that radiators ("H&C" brand)are tube type (large tube?). I based that on sections being 2.5" thick on center, and the width versus how many tubes. For example, the radiator in the photo has six tubes and that six tube section is 10.25" wide, a 5 tube section is 8.5" wide. I believe this makes it large tube and subject to the "tube" section of this table from Burnham:


    Based on that, I came up with 260 square feet of radiator, making the MST288 my choice.

    I'd love your input on a few things:

    -Does that sound about right for this size house and am I using the right table for sizing purposes? Seems like most estimates I get want to oversize it. I had one contractor tell me I needed the one rated for 513 square feet of steam.

    -Based on the photos, can anyone tell me how old the boiler is? National Radiator Corp, SN NC1449, size AO-5

    -The only main vent is seen at the very end of the condensate return in the photo. I plan to elevate and replace with a Gorton #2. There is about 50 feet of 2" main that transitions into 30' of 1.25 inch main/condensate return line running around the perimeter of the basement. The vent is at the end of the 1.25" line.

    Any thought or advice are appreciated. I have learned a tremendous amount from this site and several people have emailed me personally to take the time to answer my questions and to help educate me. I am very appreciative and will post some photos as the project progresses.

  • ttekushan_3
    ttekushan_3 Member Posts: 958
    your sizing estimate seem right

    Hi Chris-

    since your house was built in the late '30's, in the automated firing era (meaning "post coal") so heating systems were less likely to be grossly oversized. At the time 40 btu/square foot was normal. So, say roughly 1,500 square foot house * 40 btu/square foot = 250 square ft EDR. So you're on the money. The 288 is ideal from the info you've shared.

    So MY question is, if those contractors are saying to double it, what else don't they know that will affect their installation and piping job? I know that sounds overly judgmental and a bit mean, but its a serious question.

    Regarding the age of the boiler, I'd say its original to the house. It looks pretty 1938 to me. Not very technical, but what the heck. I wouldn't destroy it. I'd move it aside on a new pad. Then I'd detail it or even repaint it. Then put an accent light on it and the new Burnham. Seriously, I'd do that. My relatives consider me nuts for doing things like that, but my friends usually find it cool. You can pick your friends but......

    Regarding the mains, I think you can never vent them enough. This gets the mains to act as much as a manifold as possible. You have a great chance to dial in the balance of the system this way.

    Keep up the good work!

  • s. reja
    s. reja Member Posts: 3

    Thanks for the input. I actually like the idea of painting it up and turning it into a cabinet or something, since it is pretty cool looking in its own way. If I lived there I might do it. Where it is a rental unit I think I'll get it out of there just for space reasons and to keep things tidy and not too funky looking.
  • Stewy_2
    Stewy_2 Member Posts: 83
    Buy Mr. Holohans Books, I'm doing what your doing

    and the books have been awesome, wish I had them 2 years ago(Lost Art of Steam Heat, A+). Pretty much all the questions you have can be answered by the books. They help you become smarter on steam so you know what questions to ask in order to find the right contractor. They may also inspire you to get you own hands dirty
This discussion has been closed.