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New Gas (steam) Boiler Install Questions

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PiperPete
PiperPete Member Posts: 48
I currently have a Weil-McClain gas powered steam boiler which came with the house I purchased in 1998, so I have no idea how long it was in service. At this point it's over 20 years old and It has given excellent service since I've owned the property except in the past year. The electronic ignition unit had to be replaced about 4 years ago, and the glass tube (left side) had to be replaced 2 years ago since it became quite black with residue that would not come out. This past year it started leaking and intermittently going on/off/on. The heating tubes are working but some are rusted in place and cant be removed. Because of the leak, my presumption is a new boiler is called for. The boiler is rated at 200,000 BTU input, 160,000 BTU output. I've tried to get plumbers to provide price quotes and one, who was very prompt, provided a printed breakdown of costs, etc. The boiler suggested by the plumber is a New Yorker CGS50 138,000 BTU input - this is 62,000 BTU less than the current boiler. This size was selected by the plumber because he felt the current Weil-McClain is "over-sized". I have a two family and basement house with at least 12 steam radiators. I have not taken cubic measurements of the rooms to get total cubic space for sizing, but based on the above would you consider the reduction in BTU of the new boiler to be an issue?
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Comments

  • WMno57
    WMno57 Member Posts: 1,387
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    PiperPete said:

    with at least 12 steam radiators.

    It can be difficult to know exactly how many radiators are in one's home. Try this. Crank the thermostat as high as it will go, wait an hour, and then use an infrared camera to discover the shy radiators that are hiding.
    There is only one way to size a steam boiler. Steam boilers are sized to the total EDR of all the radiators in the house. Each radiator must be measured. You can do this yourself, or you can ask your contractor to do it. If your contractor says that method is not necessary, then he has no clue how to install a steam boiler. He will likely make other mistakes on the install that will cost you money and cause you grief.

    https://heatinghelp.com/find-a-contractor/
    I DIY.
  • random12345
    random12345 Member Posts: 469
    edited October 2022
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    Finding the EDR of all your radiators is the first step. You can try to do this on your own and/or by purchasing Dan's Book: https://heatinghelp.com/store/detail/e-d-r-ratings-for-every-darn-radiator-and-convector-youll-probably-ever-see

    Also see this: https://babel.hathitrust.org/cgi/pt?id=uiug.30112047386849&view=1up&seq=3

    And this: https://heatinghelp.com/heating-museum/category/radiators

    If you're unsure about your rads, take pictures of your tube or column type radiators front and side for each. Along with this, measure the height, width and thickness of a single section for each of them. If you have convectors, measure the convector length and thickness as well as the enclosure's internal height. Look for embossed writing or symbols around the tapping or on the sides of all the radiators. Make note of it. If you see a manufacturer name, this is often helpful. Also, when was your house built and are your radiators original to the house? Post all of that information up. We can try to help.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,153
    edited October 2022
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    Steam boilers can be very difficult for some installers. if they get it wrong, they will loose money on the job and you may be left with a system that does not work. If they try too many times to correct their inexperience, eventually they will just walk away. Then you will need to come back here for more help.

    Hopefully you can find an expert here https://heatinghelp.com/find-a-contractor/ and avoid these problems.

    You need to know the Equivalent Direct Radiation (EDR) value of the radiators that will be connected to the new boiler. This is how to select the proper size. Your plumber may be correct about oversizing, but he needs to tell you why he knows that. Did he measure anything in your home? Did he measure each radiator in the system?

    Guessing won't cut it with steam!

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • PiperPete
    PiperPete Member Posts: 48
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    Thanks everyone for your comments, suggestions, and links. Regarding EDR for radiators I was able to find a worksheet that indicates various types of steam radiators and asks for the number of columns, the number of sections, and the height - all items I can provide - and based on that info it indicates the EDR. Using that worksheet I have determined the EDR for the current radiators, total of 13. There seems to be no way to include a copy of the worksheet in this forum, but I can include the link to it: https://www.smithfieldsupply.com/company_info/forms/radiatorest.pdf

    My radiator types are the Figure 9 Columnar Radiator, at the bottom of the sheet. (Getting more specific info off the radiators is more difficult and so unlikely.)

    The worksheet says to multiply the number of sections x the EDR shown (based on number of columns) which I've also done for each radiator. But it doesn't say what to do next. So do I add up the total of all the radiators (the Sum of (sections x EDR) for each) to get a single number, and if so, what do I do with that single number to derive a input BTU? Feel free to include a formula if you can. Thanks again all for your assistance!
  • mattmia2
    mattmia2 Member Posts: 9,840
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    You add up the edr for each radiator to get a total for the system and compare it to the edr on the rating plate of the boiler. (it can be converted to btu, the edr on the boiler contains an extra 1/3 for piping which is usually more than the amount consumed by the piping so even the rating on the boiler usually oversizes it a little bit).

    The idea is that the steam the boiler produces should match the amount of steam the system consumes. If the boiler produces more steam than the system can consume it builds pressure which raises the temp which reduces the transfer of heat from the fire in the boiler to the water a bit and slows the travel of steam through the system and can cause problems with various steam control devices in the system.
  • random12345
    random12345 Member Posts: 469
    edited October 2022
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    PiperPete said:

    My radiator types are the Figure 9 Columnar Radiator, at the bottom of the sheet. (Getting more specific info off the radiators is more difficult and so unlikely.)

    The worksheet says to multiply the number of sections x the EDR shown (based on number of columns) which I've also done for each radiator. But it doesn't say what to do next. So do I add up the total of all the radiators (the Sum of (sections x EDR) for each) to get a single number, and if so, what do I do with that single number to derive a input BTU? Feel free to include a formula if you can. Thanks again all for your assistance!

    Not true. There are old trade catalogs available which are much more exact. It just takes a little bit more effort, and not as much as you might think if you can find the name of the manufacturer written somewhere on your radiator and have some idea of when your house was built. That's why I posted those links and offered to help. It's up to you, but in my experience contractors don't like to spend a lot of time online looking for these catalogs and tend to oversize. Yes they should measure your rads, but the measurement will be an approximation using one of those worksheets that may or may not be accurate enough. In my case, looking up the ratings in old trade catalogs allowed me to go down a size on my boiler with total confidence.

    To answer your question, all steam boilers have a steam rating in sq. ft. There is no need to derive an input BTU from that. Whatever the boiler rating is, generally speaking it should not be much lower than your calculated EDR from your rads.

    EDIT: That worksheet tells you to oversize by 1.25. This is incorrect. I have a Burnham Megasteam MST288: https://s3-us-west-2.amazonaws.com/catsy.782/MegaSteam+Product+Data+Sheet.pdf

    On page 2, look for "Net AHRI (sq. ft.)". That is the boiler's rated size.

  • jhewings
    jhewings Member Posts: 139
    edited October 2022
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    Many or all steam boilers have a rating called "steam square feet". You want to match steam square feet as closely as possible to your total EDR. You do not add a pickup factor in this case. You don't have to look at BTU input and output.
  • PiperPete
    PiperPete Member Posts: 48
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    Update: I thought I'd show you a table of what I've got which makes it easier I think to see my overall results:
    Total radiators in house = 13
    Floor 1 has 6 radiators,
    Floor 2 has 7 radiators,
    Basement has no radiators

    Note: EDR number is from worksheet in previously provided link.

    FLOOR 1
    Living room (2 radiators):
    5 columns x 11 sections x 22" height: EDR=6, 6x11=66
    5 columns x 9 sections x 20" height; EDR=6, 6x9 = 54
    Dinning Room (1 radiator)
    5 columns x 11 sections x 22" height; EDR=6, 6x11=66
    Bathroom (1 radiator)
    3 columns x 7 sections x 22" height; EDR=3, 3x7 =21
    Bedroom 1 (1 radiator)
    5 columns x 10 sections x 22" height; EDR=6, 6x10=60
    Bedroom 2 (1 radiator)
    5 columns x 7 sections x 22" height, EDR=3, 3x7 =21
    Kitchen - NO Radiators

    1st Floor Total EDR x SECTIONS = 288

    FLOOR 2: Same as FLOOR 1, with a radiator in Kitchen:

    sub-total EDR x SECTIONS = 288 (same as floor 1)
    + Kitchen (1 radiator)
    4 columns x 9 sections x 22" height, EDR=4, 4x9 = 36

    2nd Floor Total EDR x SECTIONS = 324

    Grand total EDR x SECTIONS (13 radiators) = 288 + 324 = 612

    So what do I do with that 612 number to derive an estimated input BTU ?

    Thank you again!

  • random12345
    random12345 Member Posts: 469
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    Read the comments above again. You may have missed them.
  • bburd
    bburd Member Posts: 926
    edited October 2022
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    @op Can you post a photo of one of these radiators? I think you may have large tube radiators rather than column radiators, because the numbers just don’t make sense.

    Bburd
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,153
    edited October 2022
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    Based on your EDR numbers, if you were to select a Burnham MegaSteam boiler you would select the model MST629. because that boiler has a Sq Ft rating closest to your EDR

    For the NewYorker CGS boiler I would choose the -80
    Now if you have radiators the are slightly less EDR per section, then you would need to look at those numbers more closely. There is a possibility that your Actual EDR is slightly lower. Since your old boiler is most likely a model ?EG-55. that had a SQ Ft rating of only 508. (the old I=B=R is now AHRI)
    If I were selecting your new boiler, I would ask "Back when it was working fine, were there any rooms that were too hot or too cold? Did the home stay warm enough on the really cold days? Are there any problems that you want the new equipment to resolve?" If your answers were that "everything heated properly" then I would go with a boiler with a 500 to 550 Sq Ft rating. Why mess with success?

    So maybe the CGS-70 is the correct boiler for you. The CGS-50 might be too small in my opinion.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • pedmec
    pedmec Member Posts: 994
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    That New Yorker is only 354 square ' of steam. You would be undersized by about 3 sections. Thank goodness you reached out and received good advice from hh.

    You would use the AHRI net rating. that is the steam available to the radiators after all other heat losses thru the pipes and fittings of the steam traveling have occurred.
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,153
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    @PiperPete Can you post photos of your radiators?

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • random12345
    random12345 Member Posts: 469
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    Repeating the instructions from above: Take 2 pictures of each of your radiators front and side for each. Along with this, measure the height, width and thickness of a single section for each of them. Look for embossed writing or symbols around the tapping (where the steam pipe is attached) or on the sides of all the radiators. Make note of it. If you see a manufacturer name, this is usually helpful. Also, when was your house built and are your radiators original to the house? Post all of that information up.

  • KC_Jones
    KC_Jones Member Posts: 5,745
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    IF your numbers are correct the current boiler is under sized and the contractor is proposing going smaller.

    The odds that you have an under sized steam boiler and getting quote to go smaller are slim to none.  It’s extremely rare to have undersized steam boiler, certainly not twice in one house, but strange things happen sometimes.

    I suspect you may have misidentified your radiator type.  I agree with above post a picture of what you have so we can verify what you are looking at.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    ethicalpaul
  • PiperPete
    PiperPete Member Posts: 48
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    Again, thanks everyone for your input. As suggested, I have take a front and side photo of the largest radiator (2nd flr, living room) and posted it. I can't access the 1st flr apartment to inspect every radiator at this time, but, having previously inspected them I do know they are all of the same type as the one I have posted two images of. Also note, that because I can't get access at this time to the 1st flr apartment I have duplicated the radiators for the 1st floor to be the same as the 2nd floor with the exception that the 1st floor has a radiator in the kitchen but the 2nd floor kitchen does not. Overall, there are 6 radiators 1st floor and 6 radiators 2nd floor. But as I said, the type of radiator you see in the posted image is the same for all radiators on both floors except for the number of columns and sections and slight height differences. Also, as I mentioned, I'm using the EDR Guide sheet Figure 9, Table 4, that states to multiply the EDR (per section) X the number of sections to get the RADIATOR EDR number.

    Now please answer this: I identify the radiator in the posted image as a "Columnar Radiator", having 5 columns and 11 sections... Is that correct that it is a Columnar Radiator or is it a Tubular Radiator.

    If it's a Tubular Radiator then obviously my numbers are wrong because there's a different table for Tubular Radiators in the EDR Guide sheet.

    So, please confirm whether the radiator I posted is Columnar or Tubular.




    The EDR Guide Sheet I'm using is here: https://www.smithfieldsupply.com/company_info/forms/radiatorest.pdf

  • neilc
    neilc Member Posts: 2,711
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    tubular man, totally tubular,

    go look at that pdf again,
    columns are wide internal spacing, and what you're showing is not,
    looks about 1/2 the edr if I read that page correct,
    (i read the edr chart quick and brief)
    known to beat dead horses
    EdTheHeaterManbburd
  • mattmia2
    mattmia2 Member Posts: 9,840
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    If you look at your pictures it is a tubular radiator. If the apartment you can't access has conditioned space above and the apartment you can access does not then the radiators in the apartment with conditioned space above should be smaller if they followed the heat needed in each room to size them.

    Using something like the edr book to find exact matches for those radiators would be more accurate but you can see for a given number of passages a column radiator has significantly more area than the tubular radiators you have.
  • random12345
    random12345 Member Posts: 469
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    Looks like large tube-type radiator. Not columnar. As I said before, we have the height, now we need the width and thickness of a single section to give you a better idea of the EDR. You have all 22" height and one 20" height. Do you see a manufacturer name anywhere? How old is the building? Throw away that worksheet, it is not accurate.
  • PiperPete
    PiperPete Member Posts: 48
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    So I have Tubular radiators... Ok, that nails one item down. For the posted radiator image is it 5 tubes, or 3 tubes? I mean do you count each vertical section as a tube, or just the 3 inner vertical sections? In short is it a 5 tube or 3 tube radiator? Thanks again for all this input!
  • JUGHNE
    JUGHNE Member Posts: 11,090
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    I say 5 tubes.
    Each of the 5 are hollow and have steam/water in them and radiate heat.
    bburd
  • PiperPete
    PiperPete Member Posts: 48
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    Ok, great JUGHNE, that confirm I'm viewing/reading the columns correctly. My previous numbers are all wrong because I was using Columnar. I will redo them all using Tubular, and see what the final numbers look like. To random12345, the radiators appear to be the originals, from 1932 (!) and the end-cap with marking is not readable. So I can't provide that info. I will also physically inspect all radiators on the 1st floor as soon as I can get access so that I can see what those radiators are in terms of number of sections, columns, height, rather than using the number from the 2nd floor which might cause the overall number to bump me to a larger boiler perhaps unnecessarily.

    So I will post new numbers ASAP.

    Meantime, thank you all for your valued input. Stay tuned!
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,153
    edited October 2022
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    Tube NOT Column.
    Your total EDR is 392. (based on your previous info)
    SO, your existing boiler IS oversized.
    Your new boiler should be between CGS-50 and CGS-60
    Your Plumber might not be so far off base.

    Getting the correct EDR is important.

    A CGS-50 might work just fine. It will depend on the type of insulation on the steam main and how well that insulation is working, That can increase the amount of steam that is actually lost in the piping & pickup. It can get you closer to the 392 sq ft, but it may also fall short. There are some articles about how undersized boilers can work in some situations. I am not sure that I would stick my neck out on this one. I would select the -60 if I were quoting the project.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • random12345
    random12345 Member Posts: 469
    edited October 2022
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    If there are markings anywhere, post them up, there's a good chance I'll be able to tell who made it. Section thickness varied between 2.5", 1.75", and 1.5". That's important to find out, so is the width. Make sure the height is 22" and not 23". My guess is the kitchen rad is either an older or newer design, and the others are newer and not original. All of this was standardized across the industry by the US Dept of Commerce. The 22" tall 5 tube rads had 1.75" thick sections and were 2.1 sq ft/section. The 2.5" thick section rads only came in 20" or 23" height and had EDR 2.67 sq ft/section. Let me know what you find out.
  • PiperPete
    PiperPete Member Posts: 48
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    Thank you random12345 and EdTheHeaterMan... and everyone else!: I will redo the 2nd floor which I have complete access to and get the 1st floor ASAP and post both with the numbers. The subtly of what a Tubular and Columnar radiator looks like is not straightforward for me since I don't work with them regularly, but knowing that I have Tubular should make the final number easier to derive. This has been an incredible learning experience. I do hope I don't have to bump the boiler up to the CGS60 as it is of course more money, but if necessary, then it's necessary. Will get back to you guys real soon !
  • PiperPete
    PiperPete Member Posts: 48
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    Ok, as I said I'd get back with an update so here it is:

    I was able to visually check each of all 12 radiators. It is not possible to read the information on them because of their position/location and deterioration (original radiators from 1932/33), so I can't get more specific details on each. However, I was of course able to measure height, number of TUBES, and number of SECTIONS.

    Using the Table 3 of the EDR Guide (source: https://www.smithfieldsupply.com/company_info/forms/radiatorest.pdf),
    I calculated each radiators EDR (EDR number x number of SECTIONS per Table 3 of the EDR Guide) which is represented in column 6 of the table I've uploaded here.

    Also note that some of the measurements for height in the Table 3 of the Guide do not exactly match what was measured so I have used the next higher height from Table 3. For example, there is no 22" high, 5-Tube radiator indicated in table 3, so I have used the next higher height of 23", 5-Tube and taken the EDR number for that and used it to calcular the total Radiator EDR. These slight discrepancies are indicated by an asterisk (*) in the table with the height measurement and the EDR selected.

    Based on the calculation using Table 3 of the EDR Guide, it appears that my Grand Total EDR comes to 316.71, 317 rounded up. The number for the New York Boiler model CSG50 Square Footage EDR is 354.

    So, the first question is: Is the total EDR of 317 more or less correct?
    The second question is (assuming the answer to the first is correct) since the EDR of 317 is less than the boiler Total EDR of 354, is that model number OK to go with without having to jump to the next higher model?


  • mattmia2
    mattmia2 Member Posts: 9,840
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    Assuming your calculation is correct for the EDR, the boiler that is 354 is slightly oversized which should work OK. That 354 has 30% added to it for the piping which is usually less steam than the piping would consume so you could likely go smaller and it would still be OK.
  • random12345
    random12345 Member Posts: 469
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    You're not following/reading my instructions. That's fine, I don't take it personally, but I can't help you unless you do. Last time: What is the width and thickness of a single section for each of your rads? The calculated EDR is not correct. Saying a rad is 23" when it is in fact 22" tall will significantly affect the total. It's a different type of radiator. Your actual EDR is significantly less. You appear to have a mix of old large tube type rads and slightly newer but still obsolete models.

  • PiperPete
    PiperPete Member Posts: 48
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    I have included the Table 3 from the EDR guide that I used so that it can be verified more easily.

    I'm certain my calculations are correct, in so far as the Table 3 is accurate.

    For example, for the Bathroom radiator on the 1st floor, it measures 25" high, has 3 Tubes and 5 sections. Looking at table 3 below, there is no 25" radiator that matches 3 Tubes. But there is a 26" with 3 Tubes and the EDR shown is 2.33. So I have used the EDR for the 26" instead since it's the closest. So the radiator's EDR is 2.33 x 5 (sections) = 11.65.

    I did similarly with all other radiators where there was not an exact match of height and tubes. Because I used the next higher radiator, I would presume also that the actual EDR for those radiators is actually slightly less than what is computed.

    Thanks for you input!


  • random12345
    random12345 Member Posts: 469
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    I believe your actual EDR is 263.56. The worksheet is wrong. A CGS40C is most likely what you need. Without the information I asked for, I can't be sure.
  • PiperPete
    PiperPete Member Posts: 48
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    Hello random12345: Sorry if it seemed like I was ignoring your instructions. I'm somewhat pressed for time because I have limited access to the 1st floor, and I presumed the Table 3 of the EDR Guide would suffice which is why I posted my table with all calculated values.

    In terms of the table values where a radiator did not match the height measured to the height available in table 3, as I mentioned, I used the next tallest with the same number of tubes: This does result in a slightly higher edr number to multiply the sections by but I opted for the slightly higher number thinking that it would be better to slightly over estimate rather than underestimate the total radiator EDR.

    I did what you asked for and measured all radiators. Here's the results:

    1 - With exception to the two bathroom radiators, all sections for any given radiator are 8" wide x 1.5" thick.

    2 - For the two bathroom radiators, all sections are 4.5" wide x 1.5" thick.

    Thank you for your help with this!



  • random12345
    random12345 Member Posts: 469
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    Ok. Is this how you measured thickness and height?


  • random12345
    random12345 Member Posts: 469
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    Did you check for any writing or symbols that were embossed or engraved into the metal (not painted) in the following areas on either side? The bottom one especially around the tapping where the steam enters the rad is where you would find some markings.


  • jhewings
    jhewings Member Posts: 139
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    If your EDR is accurate then the proposed boiler is about 12% oversized which is probably workable but if random's number is correct then the boiler is about 35% oversized which is probably too big.
  • PiperPete
    PiperPete Member Posts: 48
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    I measured the thickness of the "section" per the red line you show... which you show as not correct. If I measure using the green line as you show, then the section = 2.25" thick.
    I measured the height per the yellow line.
  • random12345
    random12345 Member Posts: 469
    edited October 2022
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    And the writing/branding? Anything at all? Are you sure the green line is 2.25" and not 2.5" thick?
  • PiperPete
    PiperPete Member Posts: 48
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    First, yes, the thickness is 2.5" not 2.25", sorry my error.
    At the areas you've marked in green I looked at 5 radiators and there are no markings whatsoever. The only marking, which appears to be the manufacturer name, is at the top where you have it circled, except at the other end, but it is so faded and corroded - on all of them - that I am unable to decipher the letters. There are no marking at the bottoms either, of any of the ones I could see or get to. The others (1st floor) are in a physical position where I'm not able to view their sides because of heavy furniture on either side which I can't move away sufficiently to decipher anything, if it's there. And I suspect they are similar to the ones I can get to in that there are no identifying marking that are decipherable any more. Keep in mind, these are the original radiators (so I was told by the previous owner) from 1932/34 when the house was built. And from the looks and condition of them I believe him. Let me know if there's anything else I can do.
  • random12345
    random12345 Member Posts: 469
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    Take a picture of the corroded marking, get it in focus, post it up. I might be able to tell you anyway. Your rads are a little unusual. Most companies made them in 20", 23" height, not 22" or 25". Those came later.
  • PiperPete
    PiperPete Member Posts: 48
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    Ok... Here's the side-end cap for the bathroom radiator 2nd flr. For the other radiators, they all seem to have this same configuration with the name extruded on the side (I know because I can put my hand on the end cap and feel it) but this was the only radiator where a camera can be positioned well enough to capture the plate. For the other radiators there's simply no clearance for a camera to get a similar head-on shot.


  • random12345
    random12345 Member Posts: 469
    edited October 2022
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    Looks like a McKeesport Radiator made by the Columbia Radiator Company in McKeesport, PA.

    https://worthpoint.com/worthopedia/antique-vintage-mckeesport-hot-water-1897551887

    You can also do a search on here for "McKeesport" and you should be able to find a few more pictures of those rads in related threads.

    If all of your radiators look like that on the side, then it's a good bet that's what you have. The problem is, I have no record of them ever being manufactured in 22" or 25" heights, only 20", 23", 26". And I have a Columbia trade catalog to prove it. This is the only one I've been able to find in the whole country, and it was scanned by a volunteer at the Smithsonian Trade Literature Collection. Cast iron radiators were eventually standardized by the US Dept of Commerce in 1940, under Simplified Practice Recommendation R147-40. Their stated purpose for doing this was to conserve metal given that WWII was happening at the time:

    https://babel.hathitrust.org/cgi/pt?id=uiug.30112109610573&view=2up&seq=7&size=175

    But Columbia Radiator Company is absent from this list of acceptors. However, in a subsequent publication, R147-41, one year later, they did accept the new standard for small tube radiators:

    https://babel.hathitrust.org/cgi/pt?id=mdp.39015035429805&view=2up&seq=1759&size=175&q1=r174-40

    A 1934 Pape-Swift radiator reference book shows a couple manufacturers making rads in 22" heights at that time:

    https://babel.hathitrust.org/cgi/pt?id=uiug.30112047386849&view=2up&seq=172

    https://babel.hathitrust.org/cgi/pt?id=uiug.30112047386849&view=2up&seq=184&size=300

    My guess is, the Columbia catalog I have was published 1941 or later, and if we could find some of their older catalogs, we would find that they made rads in 22" and 25" heights with the same EDR ratings. It might have been different though.

    Long story short...I cannot say for sure what your EDR actually is, but given the examples in Pape-Swift above, if your calculations are correct, your EDR appears to be accurate.

    If you want to get a copy of the McKeesport catalog, email NMAHLibrary@si.edu and reference the following collection: https://americanhistory.si.edu/collections/search/object/SILNMAHTL_12305

    They should be able to get back to you fairly quickly (one day possibly).