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Gas Steam Boiler -100,000 BTU or 125,000 BTU system

Hope everyone is having a wonderful weekend. It looks like I have about 266 SQ FT of steam required based on the radiator measurements (10 radiators). I am receiving conflicting reports on the size of the boiler required -100,000 BTU or 125,000 BTU system. Would any of you guys happen to have any thoughts? The guy specifying the 125,000 BTU system is saying 100,000 BTUs is way undersized so I just want to make sure I come to the right conclusion.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    What are the two boilers rated at in terms of EDR -- square feet of steam? It will be on their rating plates or in the specifications. If your square feet calculation is even close, both of them are oversized (I get a requirement for 83,000 BTUh net output with a 30% pickup factor, which is ample). If that 100,000 BTUh unit is quoted on gross input BTUh, it may be only slightly oversize -- but look at the square feet rating. the 125,000 unit is significantly too big, and will create problems.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • BrendanLead
    BrendanLead Member Posts: 9
    I am looking at the Weil-McLain eg-35/eg-40
  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    You want the EG35
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,513
    I00,000 input will be fine, no need to go any larger
  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    It's right here in the WM EG manual, as if we even had to look after hearing from Dave, Ezzy, Jamie and Ed! The "NET SQ FT" in this chart gets directly compared to the measured EDR of your radiation. It's the no-nonsense way to find the right size. And even then there's slop. Even if you had 280 sq ft I'd still go with the 35.

    It really couldn't be any more clear cut. However you go with this, go content with the knowledge that you are one of the very few people who come to this site BEFORE getting shafted with an install of an oversized boiler.

    Many people come here after having bought a house where they had the previous owner replace the boiler, and the previous owner got shafted, but the new owner has to deal with the continuing poor performance and waste. You are in a good spot.


    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    motoguy128
  • bleeder
    bleeder Member Posts: 30
    I need help using chart above Please
    I am also looking at new oil boiler for 7 steam radiators 985 sqft apartment 5 rooms hall and bathroom using to much oil Decent windows need more insulation but its time boiler is peerless 120 45 years old - Im going to replace with Burnham ms or Weil McLien Looking for help with proper replacement boiler
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,513
    @bleeder
    You should start you own new post. The correct way to size the boiler is to measure the size of each of you 7 radiators (there are charts on this site available for this or download the Burnham Heating Helper from the internet)

    Get the total EDR (square feetof steam) for each radiator and add them up to get the total EDR. Then you pick a boiler that will produce that EDR
  • dopey27177
    dopey27177 Member Posts: 887
    What is not mentioned!!
    Are you going to make domestic hot water from the boiler or ate you using a separate hot water tank and burner?

    If you are installing a coil in the boiler you will need a a larger boiler.

    If you are using a submersed coil in your boiler to produce domestic hot water you will need about 40,000 btu's extra added to the boiler capacity to produce 4 gallons of hot water per minute at an 85 degree rise in temperature to supply both heat and hot water at the same time.

    There are controls available to stop the heating process when domestic hot water is needed. That will allow the the for a lower need of supply in fuel for domestic hot water production.

    If you are using the submersed coil the 125,000 btu boiler will fit the mold.

    Jake
  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    I beg to differ. The pickup factor will handle the domestic hot water.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Dave0176STEAM DOCTORRobert O'Brien
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,513
    edited September 2020
    I agree with @Jamie Hall
    The radiation is only 66, 000 btu. No need for anything larger than 100000 input. If the domestic load s that high the boiler will stop steaming for a short time while it makes hot water and it will be fine
  • gennady
    gennady Member Posts: 839

    I agree with @Jamie Hall
    The radiation is only 66, 000 btu. No need for anything larger than 100000 input. If the domestic load s that high the boiler will stop steaming for a short time while it makes hot water and it will be fine

    I would add indirect to 100K boiler.
  • ChrisJ
    ChrisJ Member Posts: 15,661
    The EG-35 is fine but I'm betting an EG-30 could even squeak by if done right, but it would take patience and a lot of fine tuning.

    I've got an EG-40 (125,000) on a system with 396 SQFT EDR.

    I'd recommend the EG-35 in your situation. Definitely not the 40.

    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
    ethicalpaul
  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    gennady said:

    I agree with @Jamie Hall
    The radiation is only 66, 000 btu. No need for anything larger than 100000 input. If the domestic load s that high the boiler will stop steaming for a short time while it makes hot water and it will be fine

    I would add indirect to 100K boiler.
    I would take this opportunity to get my hot water generation out of my 83% efficient boiler and stop heating my whole basement in the summer (and paying to do so)!
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • The Steam Whisperer
    The Steam Whisperer Member Posts: 1,215
    A 100,000 btu/hr input boiler should work just fine. Insulate your pipes and vent the steam mains quickly and the radiators slowly, but proportionally to their air content. If your system is like most systems installed between about 1905 and 1940, the radiators are about 60% oversized for the heat loss. That means on the coldest day the boiler only needs to put out 38,000 btuhr to the radiators. Add about 7% for the piping losses ( insulated basement piping) that comes to about 41,000 btu/hr output on the coldest day. A 100,000 btu/hr input boiler outputs about 80,000 btu/hr, more than enough extra capacity to heat hot water if you need to.
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • bleeder
    bleeder Member Posts: 30
    Thank you
    Yes I do heat my hot water from my boiler currently, was thinking of putting in an electric water heater to hold a capacity of 40 gal
    water rather than 4 for the summer months.
  • bleeder
    bleeder Member Posts: 30
    most of the pipes still have that old covering on the pipes your right on the money it was built in 1925 and the current boiler went in in 1975 I can remember taking a sledge hammer to the old monster and helping Dad bag it!! and put it out in the rubbish..We threaded our own pipes etc for the new it was something to watch as a kid
  • ethicalpaul
    ethicalpaul Member Posts: 5,701
    bleeder said:

    Thank you
    Yes I do heat my hot water from my boiler currently, was thinking of putting in an electric water heater to hold a capacity of 40 gal
    water rather than 4 for the summer months.

    Have a look at two Rheem products. There is their heat pump water heater, which I bought and NJ paid me $750 in incentives and I love it and installed it myself: https://www.homedepot.com/p/Rheem-Performance-Platinum-50-Gal-10-Year-Hybrid-High-Efficiency-Electric-Tank-Water-Heater-XE50T10HD50U0/300620237

    Or there's also the Rheem Marathon series, which is a traditional electric water heater, but with a plastic tank that will never rust and has very good insulation built in. I installed one of those in my previous house in CT.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
  • gennady
    gennady Member Posts: 839
    edited September 2020

    gennady said:

    I agree with @Jamie Hall
    The radiation is only 66, 000 btu. No need for anything larger than 100000 input. If the domestic load s that high the boiler will stop steaming for a short time while it makes hot water and it will be fine

    I would add indirect to 100K boiler.
    I would take this opportunity to get my hot water generation out of my 83% efficient boiler and stop heating my whole basement in the summer (and paying to do so)!
    Why would you heat basement In the summer with indirect attached?
  • ChrisJ
    ChrisJ Member Posts: 15,661
    gennady said:

    gennady said:

    I agree with @Jamie Hall
    The radiation is only 66, 000 btu. No need for anything larger than 100000 input. If the domestic load s that high the boiler will stop steaming for a short time while it makes hot water and it will be fine

    I would add indirect to 100K boiler.
    I would take this opportunity to get my hot water generation out of my 83% efficient boiler and stop heating my whole basement in the summer (and paying to do so)!
    Why would you heat basement In the summer with indirect attached?
    Well,
    In the case of a CI steam boiler it's got a whole 1/2" of the cheapest insulation you can find and many parts aren't even insulated. My boiler gives off far more energy than my power vented 50 gal tank heater.

    When I moved in, the boiler did our domestic HW and the basement was hot from it. Indirect or not, I feel it's a huge waste vs a power vent or direct vent tank heater.

    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
    ethicalpaul
  • gennady
    gennady Member Posts: 839
    edited September 2020
    ChrisJ said:

    gennady said:

    gennady said:

    I agree with @Jamie Hall
    The radiation is only 66, 000 btu. No need for anything larger than 100000 input. If the domestic load s that high the boiler will stop steaming for a short time while it makes hot water and it will be fine

    I would add indirect to 100K boiler.
    I would take this opportunity to get my hot water generation out of my 83% efficient boiler and stop heating my whole basement in the summer (and paying to do so)!
    Why would you heat basement In the summer with indirect attached?
    Well,
    In the case of a CI steam boiler it's got a whole 1/2" of the cheapest insulation you can find and many parts aren't even insulated. My boiler gives off far more energy than my power vented 50 gal tank heater.

    When I moved in, the boiler did our domestic HW and the basement was hot from it. Indirect or not, I feel it's a huge waste vs a power vent or direct vent tank heater.

    Boiler with indirect must be wired so the boiler is off when there is no call for DHW ( in the summer), then when DHW call comes, the boiler fires up, heats to at least 160F, then the circulator kicks in. After the tank is heated, the boiler must turn off completely, with the pump running to pick up residual heat from the boiler and then turn off as well.

  • ChrisJ
    ChrisJ Member Posts: 15,661
    gennady said:

    ChrisJ said:

    gennady said:

    gennady said:

    I agree with @Jamie Hall
    The radiation is only 66, 000 btu. No need for anything larger than 100000 input. If the domestic load s that high the boiler will stop steaming for a short time while it makes hot water and it will be fine

    I would add indirect to 100K boiler.
    I would take this opportunity to get my hot water generation out of my 83% efficient boiler and stop heating my whole basement in the summer (and paying to do so)!
    Why would you heat basement In the summer with indirect attached?
    Well,
    In the case of a CI steam boiler it's got a whole 1/2" of the cheapest insulation you can find and many parts aren't even insulated. My boiler gives off far more energy than my power vented 50 gal tank heater.

    When I moved in, the boiler did our domestic HW and the basement was hot from it. Indirect or not, I feel it's a huge waste vs a power vent or direct vent tank heater.

    Boiler with indirect must be wired so the boiler is off when there is no call for DHW ( in the summer), then when DHW call comes, the boiler fires up, heats to at least 160F, then the circulator kicks in. After the tank is heated, the boiler must turn off completely, with the pump running to pick up residual heat from the boiler and then turn off as well.

    You're still heating a whole lot of things, a lot hotter than domestic hot water for no reason.

    I'll never do one.
    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
    ethicalpaul
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817
    edited September 2020
    @ChrisJ
    Never say never.
    If you have the old standard 40-gallon automatic gas water heater connected to a chimney the fire in the is about 68% efficient. If it is less than 10 years old then it is slightly more efficient. That ti the flame efficiency measured with combustion analysis equipment.

    now you purchase a new Mod/Con boiler and it operates at efficiencies over 90% AFUE. In some cases the efficiency measures with the same combustion equipment mentioned above, the test results can get as high as 96% or 97%.

    Now take that 70 efficient water tank and let it sit connected to the chimney for 24 hours. You will see the temperature drop by 10° or more several times over the 24 hour period. that is because the chimney that the tank is connected to is very good at removing the flue gas from the combustion process (A Good Thing) when the flame is on. It also is very good at moving air from the room the water tank is located when the burner is not operating. When this happens the room air travels thru the water tank, removing stored heat and taking that heat up the chimney with it.

    Now when the water heater fails, you have a choice. Replace the water tank with a 6-year warranty tank and connect it to the chimney again, or do you install a tank that is not connected to a chimney, has a lifetime warranty, and is connected to a 90+% burner that can make more hot water than you could ever use.

    Same argument for 80+% oil-fired water or steam boiler.

    The indirect tank will never lose heat up the chimney. If you let it stay idol (Use no hot water) for 24 hours, the standby loss will bring on the burner of the main heater for less than 8 minutes to recharge the tank with heat once every 18 to 22 hours.

    The rest of the time that big heater that is oversized and got the basement too hot... that only happened for a short time. Then it stayed off the rest of the day.

    When you do use the hot water for a shower or something, the burner will operate to produce the needed BTUs for the water used. It will do it faster and shut off sooner.

    The 30,000 or 40,000 BTU Burner in the Gas Automatic connected to the chimney will also provide the necessary BTUs to heat the water used. The difference is the burner in the 90+% efficient boiler wastes less than the 70% efficient burner in the gas automatic.

    Just saying
    Ed

    BTW. you are at 11,111 posts when I replied to this post.
    I wonder if this is the one(s)?

    I have some Imodium if you keep having the "ones"... and stop making fun of my speech impediment.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • ChrisJ
    ChrisJ Member Posts: 15,661
    @EdTheHeaterMan

    When I took they old boiler out that used to heat the basement I installed a Bradford White power vented 50 gal heater.  I'd even consider a direct vent these days.

    I wanted the better 2" insulation version but it won't fit down my stairs.

    These days I'm running a recirc loop with a taco 006 SS and an aquastat.

    But no, no indirect for me.


    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
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817
    edited September 2020
    Are you talking about self-use only? With over 11,000 posts, I thought you were in the trade. I believe that an indirect is a great option for some customers. Lower fuel bill and unlimited hot water. Your thoughts?

    A better insulation model can be duplicated by adding a water heater insulation wrap. insulation is insulation. no matter who puts it on the tank
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 15,661
    Are you talking about self-use only? With over 11,000 posts, I thought you were in the trade. I believe that an indirect is a great option for some customers. Lower fuel bill and unlimited hot water. Your thoughts?

    For my situation with a cast iron steamer I feel it's a poor choice.

    I have 11,111 posts now?!?  Holy cow.
    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
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817
    edited September 2020
    AGREE. If you have a tankless coil and you wanted to save on operating cost the indirect would be better than the coil. The Power vent is also better than the coil. That Gas power vent tank operates more efficiently, and the vent is not a heat thief like the standard chimney connected type.

    Are you in the business? ...or do you just like to talk a lot?
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,965
    Everyone's opinion is welcome on heating help. Everyone has what to offer. 
    EdTheHeaterManmattmia2
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817

    Everyone's opinion is welcome on heating help. Everyone has what to offer. 

    Agree

    I'm just amazed at the number of posts. I have less than 1000 while Hot Rod Bob, DanH, Jamie Hall that those guys from California & Alaska are way up there. But Dan (and company) have experience with many many customers. 11.111 posts for a DYI is amazing. And it appears that he knows the right questions to ask. and has multiple areas of expertise in the DYI department.

    Kudos to @ChrisJ Still like to know his Day Job?
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    mattmia2
  • ChrisJ
    ChrisJ Member Posts: 15,661
    Everyone's opinion is welcome on heating help. Everyone has what to offer. 
    Agree I'm just amazed at the number of posts. I have less than 1000 while Hot Rod Bob, DanH, Jamie Hall that those guys from California & Alaska are way up there. But Dan (and company) have experience with many many customers. 11.111 posts for a DYI is amazing. And it appears that he knows the right questions to ask. and has multiple areas of expertise in the DYI department. Kudos to @ChrisJ Still like to know his Day Job?
    Hi Ed,

    Thank you.
    I'm a machinist and CNC programmer.



    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
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,513
    Gee I got 1281 and I don't think I'm smarter than Chris LOL The best site around with all kinds of contributors
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817
    @ChrisJ
    Thanks for the reply, I just recently retired from owning my own HVAC Business. I specialized in Hydronics and oil heat. Been doing it for over 40 years now. I also like woodworking and have just started watching Machine Shop Videos on youtube. Working with metal is very interesting. Also, building stuff from scratch is fun.

    I have also looked at some of your previous posts. they are very informative also. Very enjoyable to watch your progress thru each adventure.

    Ed
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • mattmia2
    mattmia2 Member Posts: 9,623
    that only counts thew posts after the new system. there are the old wall posts from when if you took to long to hit submit your post would disappear too...
  • KC_Jones
    KC_Jones Member Posts: 5,736
    ChrisJ said:



    Everyone's opinion is welcome on heating help. Everyone has what to offer. 

    Agree

    I'm just amazed at the number of posts. I have less than 1000 while Hot Rod Bob, DanH, Jamie Hall that those guys from California & Alaska are way up there. But Dan (and company) have experience with many many customers. 11.111 posts for a DYI is amazing. And it appears that he knows the right questions to ask. and has multiple areas of expertise in the DYI department.

    Kudos to @ChrisJ Still like to know his Day Job?

    Hi Ed,

    Thank you.
    I'm a machinist and CNC programmer.





    Chris you are downplaying your skill set pretty dramatically.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    ChrisJ
  • JohnNY
    JohnNY Member Posts: 3,229
    @EdTheHeaterMan There are people here who comment on every post and so their numbers are astronomical.
    I've always thought it was odd that there are actual steam hobbyists out there, and even more so that a lot of them are very well informed. Personally, I deal with heat all day long and the last thing in the world I want to do is chit-chat about it after work. Anyway, the "hobbyists", if they'll allow the descriptor (I suspect some won't), used to bother me. But quite a while ago I began to admire that this is a truly an interesting group and while some troublemakers have come and gone over the years, I like the "all are welcome" approach and I encourage my clients and staff to use the forum as frequently as they can. I've got enough faith and confidence in myself to hang my hat anywhere in this industry and I'll go shot-for-shot with anyone. Except @Steamhead . He's from another planet.
    Please forgive the rambling post. My point is that some of these not-trade guys are pretty solid. All of them seem to know how to read the room and they back off when it's time for someone else to take the floor. That said, I've only got 2,300 posts and I still consider myself a regular participant and active user.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
    Classes
    ethicalpaulPrecaud
  • JUGHNE
    JUGHNE Member Posts: 11,060
    There are "visits", "posts" and "points".
    I am not sure how the "points" system works, but somehow I have made it to the top ten??? IDK

    I consider myself as both a "hobbyist" and an actual tradesman.
    I do get paid for working on systems. But, I spend more time here than actual billable hours at the job.
    As I told my brother whose hobby is restoring Z-cars, that my hobby actually pays me.....most of the time....and his does not...ever.
    I am one of the fortunate ones who enjoys fixing problems, even if it is cleaning a wet return or venturing into a crawl space to correct slope on steam mains.......however the romance is starting to fade on some of this physical stuff as I turn 71.

    There are quite a few homeowners who have studied and even installed their own systems who are are up to par with some pros. IMO
    ethicalpaulPrecaudluketheplumber
  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    I would class myself as one of those "hobbyists", @JohnNY , and I have enormous respect for those of you who are actually in the trade. I don't always know when to shut up, but I try... ! And this forum is absolutely invaluable. Only one like it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    ethicalpaul
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,513
    The" hobbyists" know there systems better than any pro could because they live with it day in and day out.

    I used to service a lot of big commercial burners back when I started. Schools for example if you had a service call in the city and you asked the custodian, "whats the burner doing or when did it lock out" you would be on your own. You got a blank stare

    If you got out in the sticks on a call the custodian could tell you everything the burner did. The motor started, the linkage moved on prepurge, the pilot solenoid clicked etc

    They lived with it
    mattmia2ethicalpaul
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817
    edited September 2020
    I guess my mother was right.  She would say that “people see you from their eyes”.  So I’m looking at the ones with more knowledge of a subject from my perspective.  A tradesman of over 40 years.  

    Off topic: I would use that quote whenever someone indicated that I was “less than honest”. At that point I would pack up my tools and suggest they hire one of my competitors they could trust.   At that point the customer would either decide to trust my diagnosis or I would leave.   Basically I was calling that customer the crook that he thought I might be.

    Once you get over the trust issue with a customer, The job becomes a whole lot easier. 

    @“Jamie Hall” @JohnNY. Thanks for the insight 


    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    ratiobleeder