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Do I need a boiler this big? It seems so . . .

Al Letellier_9
Al Letellier_9 Member Posts: 929
I agree with Kevin that you should recheck your calculations or have a pro do it. Most boiler manufacturers allow for the pickup in their ratings so just use the connected load and match up to a boilers square feet of steam rating. That should do the trick. By adding in the pick up factor, you are increasing the size of the boiler.


  • Daniel_3
    Daniel_3 Member Posts: 543

    I'm looking into a new heating plant for my one pipe steam and it most likely will be a Burnham Independance. After calculating the connected load AND the possible two radiators I plan to install in the attic at a later date with a 1.5 pickup, I get anywhere from 756 sqft steam to 807 depending on the radiators I plan to use. This means I'll need an 8 section and possibly a 9 section. My house is half maybe 1/4 insulated with only a half the windows replaced. I do not plan on any insulating in the future but including the rest of the replacement windows. As it stands my house is at a decent comfort level with the old unit and the third floor finished attic closed off for the past three winters which at about 336 sqft has only one american arco standing rad with 36.8 edr. I'm wondering if I'll need to add two peerless wall rads with combined edr of 42 or two eastwood standing rads with combined 76 edr. I wonder how much heat will be lost to the attic when it is opened for the winter? If I add the peerless wall rads it will need the 8 section, if the eastwoods it will need the 9 section. What to choose? All this assuming the new install will include two new end of the main vents with all the pipes already insulated and the pickup factor already factored in.
  • kevin coppinger_4
    kevin coppinger_4 Member Posts: 2,124
    the 1.5 pickup...

    factor is too large. I would use a 1.33 or 33%. This is assuming that there is not a huge amount of piping in the basement. That is a lot of EDR...you might want to re-check the calcs again or have someone else run it through. kpc

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  • Jed_2
    Jed_2 Member Posts: 781
    Maybe he's figuring

    on uninsulated, existing piping?

  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    Need Heat Loss & insulation re-calculate

    You really need to get an accurate heatloss of your home to base your sizing decisions on, especially with a steam system. Agree with comments on pick up factor -too large.

    In your post, the attic was not heated before, now with a heated attic, that will change the heat load requirements for the floor beneath - lowering it, lowering your total.

    You also state that the house is 1/4 insulated with only half the windows replaced. You don't state what your fuel bills are, but I think it would be a wise investment to consider insulating at the same time as the construction takes place if possible. If you re-caclculate your heat loads based on insulating and you will probably need a boiler half the size that you think. That will help pay for some of the insulation.

    I am attaching a boiler sizing chart, to the best of my knowledge, originally published by Weil Mclain over 20 years ago. I use it as a double check agains my manual heat loss calculations.

    Remember - this is an estimating tool. Take a look at a 1500 sqft home, construction code 1 - the table shows a heat load of 62,830, This is a home with single pane glass and minimal insulation. Now look at code 9, which is more representative of modern construction. Code 9 has a heat loss of 37,000.

    The code 1 home has a heat loss almost 70% higher than the code 9 home. Another way to interpret that would be to say the fuel cost for the code 1 home could be 70% higher than the code 9 home.

    While this isn't exactly true, you use fuel for cooking, hot water,etc., it does demostrate what insulation will do for you.

    Keep in mind, as you have apparently done, that the existing radiation, sized correctly or not, needs to be figured into your plan.

    If you plan to stay in the home (which I presume since your building on), it would be very wise to consider insulating. It will reduce you current fuel bill, reduce the cost of your new heating equiptment, increase the value of your home, and provide you a substantial payback year after year. Hire a professional to guide you through this major undertaking. A mistake in this situation is not easily undone.
  • Daniel_3
    Daniel_3 Member Posts: 543

    Yes all the pipes are already insulated. I checked and rechecked the calculations according to the actual radiator heating square footage as recorded in the Ideal fitter for the cortos and on the Heatinghelp library for the radiantrim, sunrad, and arco thin tubes. The Eastwood radiators I have were matched with the corto measured square footage. My house is approximately 2,800 sqft gla. This edr was then multiplied by 1.5 for the pickup but as you guys say Burnham may have the pickup already worked into the sqft. steam rating for the Independance series. I could rather use 1.33 like you say Kevin. My two mains are about 33 and 35 feet a piece and then we have to include the third floor with 1" inch pipe for one radiator, second floor with a mix of 1 1/4" and 1" piping for 6 radiators, and the first floor with mostly 1 1/4" piping for 8 radiators and a small radiantrim. I have 15 radiators as connected load at this moment.
  • Daniel_3
    Daniel_3 Member Posts: 543

    Thanks for the chart and the info, Glenn. Not much construction will actually be taking place as only the boiler will be installed. Current piping throughout is in excellent shape. I will install all the piping for future radiators. I will just need to know whether they will be required or not. There will be no more walls torn down in the future for any projects since I am pretty much through with renovations. There are some walls that still have plaster/lath on the second floor but have blown in insulation from the attic renewal a few years ago. A genuine heat-loss is called for of course and I will most likely have a pro come by for that math work and measurement.
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