Dunkirk v. Williamson/Weil McClain
The contractor is replacing my oil fired Dunkirk ESC3100 steam boiler with a natural gas fired Williamson/Weil McClain steam boiler. The Dunkirk has an output of 116,000 BTU/HR, the Williamson/Weil McClain has an output of 125,000 BTU/HR. From the Replacement Boiler Sizing Chart calculation, the total square feet of radiation is calculated at 208.3 with 7 radiators. The total BTU/HR load is 49,992 Is the Williamson/Weil McClain adequate? The house is 1,240 square feet of living space.
The Williamson/Weil McClain manual shows 1 supply riser at 2 1/2 inch to a 2 1/2 inch header. The Dunkirk has 2 supply risers at 2 1/2 inch to a 2 1/2 inch header. I also want to go with a 3 inch drop header, now. Would this be better than the standard 2 1/2 inch header?
Comments
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what is the edr of the boiler? sounds like the boiler is oversized by like 150% if your edr to btu/hr conversion is correct.
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the boiler should be about 55,000 btu/hr output or the closest next size up. the output of the boiler matching the amount of steam the system can consume is as important as the near boiler piping. as long as the piping meets the minimum specs in the manual it shouldn't be a problem in a boiler that small.
an eg30 is the right size boiler for that system.
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Go with the Williamson, Same as w/m. I’m pretty sure the Williamson has 2 risers ….
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The GSA-150 is much larger than you need. Assuming that your radiator calculations are correct. Get the 75 if possible. Lots of places don't carry the 75. You can also get the 100 and you'll be fine. Pure waste to get the 150.
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I would use the GSA-100. Your radiation is 208 square feet. The gsa 100 is rated for 258 square feet. Forget about BTUs etc. The only number you have to look at is the square foot or EDR rating which is the same thing. Your contractor is way off base. The smaller boiler will cost less $$$ and require less piping.
Forget the drop header with such a small boiler it is a big waste of $$$. Insist he follows the MFG instructions in the manual for the piping and pipe sizing and skimming. That's what matters. With a contractor so far off on the sizing I would look for someone else if he doesn't cooperate.
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And make sure that there is a strategy in place for keeping the water clean.
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My house is about the same Sq. feet as yours (two story) with 9 radiators for about 347 EDR, my boiler is rated at 300 Sq. feet, obviously undersized, the house heats just fine when it is Zero Fahrenheit outside. Obviously no pressure issues, more dissipation that steam supply. The basement pipes are insulated. My whole system may be a bit oversized for this house, but the radiator count kind of matches the number of rooms. I suppose they could have went with smaller radiators but with the age of the house they probably sized the system with the windows open a bit to fight the Flu. And I don't know the size of the original boiler.
If your 208.3 EDR (assuming it is accurate) with 7 radiators heats the home just fine on the coldest days I'd almost be tempted to go with the GSA-075. Most folks don't like to go smaller than the EDR, in my case it works great.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
On their estimate sheet they rounded up the radiator size and then chose the boiler the next size up from the one that would be slightly oversized. I don't get that. The radiator(s) can only condense a limited amount of steam. That is why you match the EDR (Equivalent Direct Radiation) to the Square Foot rating of the boiler. Greatly over sizing the boiler makes no sense, functionally useless, costs more, and causes pressure issues. Pressure builds since the radiator(s) can not condense the steam at the rate it is being produced.
Maybe it is the one they have in stock.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
Dunkirk v. Williamson/Weil McClain
The Dunkirk steam supply is probably horizontal the Williamson is probably vertical. With the horizontal supply type the extra pipe capacity helps. You probably don't need the drop header unless the distance between the boiler and the main pipe is limited. The drop header may provide better steam and water droplets separation but it may be overkill. If you just want it, it probably won't hurt anything except your wallet.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
Either boiler you mention is wildly oversized for your application, assuming your EDR figure for the radiators is anything like right. I'd go with the Williamson or WM. I'd agree with @109A_5 — the GSA-075 is the correct size, though the GSA-100 will work OK.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England1 -
I would use the GSA-100. Your radiation is 208 square feet. The gsa 100 is rated for 258 square feet.
Very respectfully to my good friend @EBEBRATT-Ed why would the recommended boiler be 25% larger than the radiation EDR when we know that boiler's rating already includes a 33% extra factor in it?
Myself, I wouldn't allow anything other than the 75
In fact, my EDR is almost identical to yours. I chose Peerless and their smallest one is slightly oversized for me, but it's fine. You will never be chilly with a 75 unless you choose to be, it will make plenty of steam for your system.
NJ Steam Homeowner.
See my sight glass boiler videos: https://bit.ly/3sZW1el
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Do not let them install the 150, that's quite simply insane.
I'm with several others, the 75 is plenty for your application.
I will never understand why they take the trouble to fill out the sheet, then totally ignore the numbers.
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The contractor swapped out the boilers this morning. The replacement is the GSA-100.
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That's weird, they give a "steam btu" that has 30% subtracted from it for a pickup factor. the actual pickup in a small residential system is more like 10%.
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The Replacement Boiler Sizing Chart was done when the original boiler, a refrigerator-size boiler converted from coal to oil, was replaced with the Dunkirk ESC3100 16 years ago.
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The contractor swapped out the boilers this morning. The replacement is the GSA-100. The Replacement Boiler Sizing Chart was done when the original boiler, a refrigerator-size boiler converted from coal to oil, was replaced with the Dunkirk ESC3100 16 years ago.
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The contractor swapped out the boilers this morning. The replacement is the GSA-100.
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The contractor swapped out the boilers this morning. The replacement is the GSA-100. The Replacement Boiler Sizing Chart was done when the original boiler, a refrigerator-size boiler converted from coal to oil, was replaced with the Dunkirk ESC3100 16 years ago.
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The contractor swapped out the boilers this morning. The replacement is the GSA-100. The Replacement Boiler Sizing Chart was done when the original boiler, a refrigerator-size boiler converted from coal to oil, was replaced with the Dunkirk ESC3100 16 years ago.
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The contractor swapped out the boilers this morning. The replacement is the GSA-100. The Dunkirk ESC3100 performed fine for me (even though now I see it was oversized) for 16 years until it blew a hole at the top of the rear section. So, for the replacement, I reluctantly went with natural gas. I prefer oil, but with the per gallon price approaching $6, $6,000 to fill my 1,000 gallon tank is too much. I don't think we'll be seeing oil less than $2.80 per gallon anymore.
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The contractor swapped out the boilers this morning. The replacement is the GSA-100. The Replacement Boiler Sizing Chart was filled out 16 years ago when the original boiler, a refrigerator-size boiler converted from coal to oil, was replaced with the Dunkirk ESC3100
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You won't prefer oil once you see how nice your natural gas system works.
I see that your contractor swapped out the boilers this morning (x7 😅 )…you picked an interesting time to ask for advice 🙂
Anyway to add on to other stuff you asked about, you don't need a drop header, and all you need is for the contractor to actually open the installation manual and make the piping look like the pretty picture inside there. Trust me, this is not easy. Don't pay them until you verify this and/or ask us for help verifying it.
NJ Steam Homeowner.
See my sight glass boiler videos: https://bit.ly/3sZW1el0 -
…..but I always like to hear that low rumble of the burner firing, knowing that steam heat will soon be on its way.
Yeah, after the contractor swapping out boilers 7 times, his back gave way. Anyway, being that you guys took the time to answer, I feel you guys deserve being responded to.
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Going forward, keeping the water clean, should definitely be on your bucket list
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We're always at the mercy with what the water company gives us (no well water here).
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City water is fine, the question is what you do with it. Or do like I do and use distilled.
Absolutely minimize the fresh water that you add to the boiler, that's about the only rule.
And boost the pH to 10 or so if you really want it to last.
NJ Steam Homeowner.
See my sight glass boiler videos: https://bit.ly/3sZW1el0 -
Proper cleaning of the boiler water, is highly recommended
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Regardless of where the water comes from
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