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Honest EDR & BTU calculations - Advice Needed - Gas Steam Boiler Replacement

I'm looking to educate myself so I don't get taken advantage of when I replace my old steam boiler. The old natural gas steam boiler has leaks in the tank. Fixed one another pops up. Its almost 100 years old, converted from coal and needs to be replaced. Not worth the headache anymore.

Radiator system works great though. Whole church heats up quickly when the old system is firing.

The majority of my radiators are 36 inches tall and 8.5 inches wide with 5 tube design.
Figure 8 in the below doc is the type.
based on chart EDR per section should fall between 4.5-5.

I have approximately 320 sections of the 36 by 8.5 5 tube design. (there are few radiators of different sizes but my estimate should be very close when accomodating for size differences)

Therefore I'm looking at 320 x 1.3 (piping) x 5edr x 240btu = 499,200 btu

Is my research and thinking accurate?

Do I need at least 500,000 btu? The owner of the building swears he used a 250,000 btu steam boiler to heat a 22 unit apartment building in CT and thinks we only need something that size? Radiatorwise, I think the church actually has less radiators than a 22 unit apartment building, but math seems to dictate around 500K btu at least.

Had a guy from a boiler company drop by, and he's getting my numbers now on radiators to come up with more formal estimate but he threw out 1.5-2Million BTU based on seeing the church from outside. He also threw out some astronomical numbers for cost I should be expecting, that was a bit upsetting.

The two boilers I'm seeing that could work if my calculations are are accurate:

D249 series.
H3 Series

Any other recommendations? Do you think I could get away with less btus? Is the younits site legitimate?

BTW, the church is in Denver. Does altitude effect any of this ie water boils at 203 degrees rather than 212.
Thanks in advance for any and all help in clarifying things for me. I really can't afford to be taken advantage of.

- SteamChurchBoiler (Adam)


  • Jamie Hall
    Jamie Hall Member Posts: 22,893
    Take it from the bottom. Yes, the altitude does have an effect, but you can ignore it.

    Now. Sizing the boiler. You need a boiler with an EDR rating of about 1600. That rating is part of the boiler information. For instance, a Weil-McLain 580 just happens to be rated at 1600 square feet of steam. That includes your 1.3 factor for piping. Don't worry about gross btu input or net btu. Just go with the square feet.

    And it's nowhere near 2 million BTUh! Your own figure isn't too far off -- but it's a lot easier to go with the boiler manufacturer's own rating.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • KC_Jones
    KC_Jones Member Posts: 5,692
    I just looked up your rads and on the chart I use I get the same 5 EDR per section. As Jaimie said you compare the 1600 EDR directly to the manufacturers rating. If your contractor proposes anything bigger they don't know what they are doing. 1.5-2 million is ludicrous. Where are you located? We may be able to recommend a real steam expert in your area.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • Fred
    Fred Member Posts: 8,542
    edited February 2017
    I don't know who makes Younits but the one in your first link is a hot water boiler, not steam. The second one is a steam boiler but it looks like it has side tappings for the steam risers. Those can be problematic as they tend to throw water up into the risers causing wet steam. Additionally, I would think you'd want a product that can be serviced (with local parts inventory) I'm not sure you will find parts for the younits locally unless they are interchangeable with one of the major brands. I'd be inclined to use a major brand like weil McLain, Burnham, Peerless if your installer sells those or another popular brand.
    You probably should post a picture of one of your rads so we can see if your calculation is correct. Assuming it is, steam boilers have a Net Sq. Ft. Steam rating on the boiler plate. Select one that has a net steam rating as close to your calculation of 320 X 5 = 1600 EDR. The additional piping and pick-up factors are already built into the boiler (in the net BTU rating for the boiler).
    Also, correct installation is as critical as the equipment itself. If your steam guy doesn't know steam, find someone who does. Near boiler piping must be correct, header sized correctly, mains pitched and vented properly, AND if he doesn't do an actual radiator survey and accurate sizing, I wouldn't use him/her. The size of the building isn't a good gauge. You need to size the boiler based on the connected EDR.
  • Ironman
    Ironman Member Posts: 7,342
    I totally agree with what Jamie and Fred have stated - especially the part about using a knowledgeable steam contractor.

    Those Yountis boilers look like re-badged Dunkirks. Not my favorite for steam, but they'll do okay IF they are piped CORRECTLY with a properly sized drop header. We'll be finishing up one tomorrow.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Zman
    Zman Member Posts: 7,542
    You cannot completely ignore altitude on the boiler sizing side of things. Boiler manufactures will list their deration percentage in their I&O manual, they generally are between 2%-4% per thousand feet in elevation.
    There are handful of Denver guys on this site that could like point you towards a good steam contractor.
    @Mark Eatherton
    @delta T
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Jamie Hall
    Jamie Hall Member Posts: 22,893
    Certainly close enough to ignore for sizing the boiler. Now when you got to set up the burner... then it does make a difference, but you are going to set it up with test equipment, so...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Abracadabra
    Abracadabra Member Posts: 1,948

    Had a guy from a boiler company drop by, and he's getting my numbers now on radiators to come up with more formal estimate but he threw out 1.5-2Million BTU based on seeing the church from outside.

    Stay away from that guy..

    If your calculations are correct.. 1600 sq.ft. EDR is the number your new boiler needs to match.

  • John Mills_5
    John Mills_5 Member Posts: 950
    The "boiler" in the first link looks like a Raypack pool heater!
  • ChrisJ
    ChrisJ Member Posts: 15,441
    So really, piping aside you need 384,000 btu/h to fill the radiators.

    If you want a piping factor, which, you probably should have especially on a large system, anything from 442,000 to 500,000 btu/h DOE output will do.

    What you don't need is 1.5 to 2 million.

    500,000 is the absolute highest I'd go. Just make sure you're reading the DOE output because the steam output already includes the 33% standard pickup, so for that spec you'd want 384,000.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • PinkTavo
    PinkTavo Member Posts: 64
    edited February 2017
    I am one of those Denver guys. I would suggest you get ahold of Dave Stroman of Stroman Plumbing and Heating located in Aurora, CO. He is a contributor on this site. He is knowledgeable in Steam and honest.

    Dave helped me get my one-pipe system into shape and re-fitted radiator locations and height (to accommodate a 3/4" new hardwood floor overlay).
  • SteamCoffee
    SteamCoffee Member Posts: 123
    Burnham says most of their boiler ratings are good to 2000ft. MSL. After that, its a 4% reduction for every 1000ft. That's roughly 12%. Something to consider. Older texts books always have added for spaces that aren't always heated e.g. Churches. Denver also has many winter days where the outside temp is 60+ only to fall into the upper 20's a few hours later. Ditto on Strohman Plumbing...
  • WayneMech
    WayneMech Member Posts: 53
    I have worked on a LOT of boilers in Churches! Most of that work was because the last person to touch the system was, shall we say, under-qualified. Be very careful. Some contractors see Churches as "Easy Money", because the Boards do not know what they are doing. Ditto what the above posters have said. With a boiler of this size (500kbh), you should be able to get staged firing. This saves a lot of money, operationally. With a system that old, they may include replacing all the vents. I have done this before, and it was a good decision. The added cost is almost negligible, but well worth it. Before final payment, have the contractor walk you through the entire system, explaining what should be happening when, and why. Have him review the installation with you, ensuring everything is in accordance with the Installation Manual, and applicable code. If an Inspectors Certificate is required, get it in hand prior to final payment, as well.
    Godspeed, my friend.