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 System
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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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A few things; How often do you fill that 1000G tank ? For that money that's about 6 years worth of NG for me. and my system has a larger EDR than yours and a NG fired water heater tank. Maybe it is a regional pricing thing.
I would never want oil, way too maintenance intensive. My house is so quiet in the winter, almost makes you wonder what heats it. If I wanted some acoustic feedback of burner operation, I'd find something more pleasant than the roar of an oil burner.
"knowing that steam heat will soon be on its way" My heat is fairly uniform, I never need to wonder.
Make sure they skim it, to get the oil out.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System1 -
" 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 "Wait What ???!!!
So the present contractor never did an EDR survey of your radiators ??? That does seem to explain some of the dysfunction going on.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
The MOST important thing about water is not to use more than you need. You mentioned the old boiler rotting a hole in it. You don't want the new one doing this in the future.
I would advise not using an automatic feeder (especially at first). Keep an eye on the water level. When you add water you add oxygen that causes corrosion. So you want to keep that at a minimum. Air vents can leak water or steam. Radiator valve packings can leak. A few small leaks can add up. just keep your eye on things.
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I'd fill the tank one a year at the end of the heating season, you know, late spring or early summer when the price was low. I stopped doing that a few years ago when the Cash Heating Oil website started tying their price more closely to market conditions. A lot of times the price would fluctuate daily! It IS hard trying to time the market.
The reason for such a big tank, a previous owner heated their hot water. When I got the house, it had a gas water heater.
I'm a "not liking to keep all my eggs in one basket" type of guy, hence the preference for oil. And I've learned to do the maintenance myself. The operation of the burner wasn't a roar, it was more of a subdued low rumble, noticeable but barely. But now, I'm embarking on a new adventure.
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Well, the Replacement Boiler Sizing Chart would be the same. The radiators, their number, dimensions and locations, remain the same. I just presented him with the calculations I had on file. Nothing changed. It's like, 'Do you have to survey a property every time it's sold?
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was it accurate the 1st time?
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" 'Do you have to survey a property every time it's sold? " Around here I think they do. However I don't know the rules regarding that. And funny it often causes issues .
To me trusting someones else's data could cause problems and why was that boiler oversized ?
With that much fuel use (or maybe just cost) I wonder if the system has other efficiency issues.
National - U.S. Gas Boiler 45+ Years Old
Steam 300 SQ. FT. - EDR 347
One Pipe System0 -
The boiler that came with the house was the size of a refrigerator. It was converted from coal to oil. It wasn't efficient. It never leaked. It was a beast, it just wouldn't die. That was when America really built things to last, not like the things built today. I expect the new boiler to fail sometime in the distant future like my Dunkirk did, what with the quality of water being what it is, from the water utility.
I never used an automatic feeder. I like to know what's going on with the boiler, so I rather maintain the water level myself.
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Based on the formulas in the chart and following the directions, the EDR of 208.3 was the calculated result. The result would be the same as nothing has changed since the first time.
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Around here, they do too. I never understood why a property has to be surveyed every time it's sold if the dimensions don't change. I can understand if it was added to with a neighboring property or a part of it was sold off.
The Replacement Boiler Sizing Chart calculations are correct based on the data input. I had the Dunkirk installed before I found out about this site, I didn't know it was oversized. It performed as intended up until it needed to be replaced.
Overall, I really didn't use an exceptional amount of fuel. I used between 700 to 900 gallons over the heating season, based on how rough the seasons were from year to year. I averaged about 100 to 130 a month.
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