Convert Boiler Back to Coal?

Modern and vintage hand fired coal stove are similar to a wood stove and in some cases can burn either. They need to be regulated and fed by hand usually every 12 to 24 hours depending on your usage. They require no power to operate making them ideal for rural settings with long power outages.
Coal Jockey
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Post Wed. May. 07, 2008 4:08 pm

I'd bet that puppy if hand fired would hold a good fire for 12 hours with no significant drop in pressure. You'd only have to shake and stoke twice a day under normal circumstances. I'd like to ram that thing right full of nut and watch the steam gauge spike...divert some to run an electrical generator....go off grid....

Buy yourself a good coal shovel and skip the stoker. :D

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LsFarm
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Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland
Location: Michigan

Post Wed. May. 07, 2008 9:00 pm

Hi smrfld.. when I first started burning coal, stokers really confused me too. I'll try to explain how an underfeed stoker would work in your boiler... That photo of my blue 'Iron Fireman' shows the blue cabinet, it is a hopper, it holds about 300# of coal... the bottom of the hopper is 'V' shaped, and at the bottom of the 'V' is a screw-auger,, this auger is run by a gear-reduction transmission, powered by an electric motor. This electric motor also powers a combustion fan.

The auger pushes the coal down a tube to the bottom of a pot, sort of like a steel flower pot, the coal is pushed in from the bottom, filling the pot from the bottom up.. the sides of the pot are perforated with many air holes, and the combustion fan forces air through the coal in the pot... at the top surface of the pot, there is a ledge all the way around, to catch and hold the coal as it is fed up from the bottom...

The coal fire itself is on the top of this bed of coal, that has air being forced through it.. as the coal burns it gets pushed further to the outside diameter of the surrounding ledge around the pot,, eventually burning completely, and falling off the edge into an ashpan below the pot.

The boiler has temperature sensing controls [an aquastat for water boilers] that turn the motor in the stoker on and off as heat is needed by the boiler to maintain temperature or pressure. The stoker maintains an idleing fire between calls for heat.

The beauty of a stoker over hand feeding is it lengthens the time between loading and removing ashpans.. Which gives you freedom from having to be home every evening and morning to shake, feed and empty the hand feeder

The stoker I showed was designed to turn hand feed boilers like yours into stoker feed.. to make life easier for the homeowners.. And to compete against coal-to-oil conversions. These stokers were installed through either the ashpan door or through a lower loading/cleaning door, replacing the grates.

I've attached a few more photos to go with the above text.

Greg L
ironfireman1.jpg
Transmission, motor and combustion fan
ironfireman4.jpg
feed auger in bottom of hopper
boxedring.jpg
iron firepot, with rows of air holes,, my homemade perimeter ring
14fireFlash.jpg
You can't see the flames very well, but they are about 16" tall, the flash washed them out.
14fire.jpg
same fire, no flash,, this fire is about 200,000 BTU.
Burning Pea/Buckwheat through an antique stoker [semi retired SSboiler],
Running an Axeman-Anderson 260M boiler burning Pea, About 150-250#per day
Farming, Fixing, Fabricating and Flying: 'spare time' what's that?

smrfld
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Post Fri. May. 09, 2008 8:10 am

HaHa. Every question you answer generates several new ones. To install the stoker [thanks for the add'l pics] it would need to be perpendicular to the ash door - or in my case, where the oil burner is installed. The front of my boiler is about 4 feet from the basement wall. Is that enough room for the stoker or can I put the stoker to the side and have that feeding tube at some kind of an angle? Either position would place the stoker conveniently beneath a basement window for easy loading!

You fabricated the bowl. My boiler is about 4 feet deep - do I need to fabricate a proportionally larger bowl? BTW, It must be tricky cleaning the ash out with the stoker in the way!

Does the stoker work like an oil lamp - pushing out more coal as needed and retracting it when not? By your explanation, there are two temperature controls. The thermostat, which would call for heat or not, and the boiler's temperature monitor that regulates the amount of coal and therefore, manages the temperature inside the boiler and consequently, the pressure in the system. The oil burner maintains a constant temperature and I haven't seen a gauge of any kind that indicates internal boiler temp - other than the pressure gauge - but that doesn't seem to control anything. Any idea what was replaced at the flu on my boiler? Was that the temperature management? Why would they have reduced the diameter when installing that new flu pipe [duct?]? Does that compromise anything in managing the heat/pressure?

I definitely don't want to blow up the house!

Last question .. what is the cost of a stoker? You are in PA, so pick-up isn't a big deal.

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CoalHeat
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Stoker Coal Boiler: 1959 EFM 350
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Coal Size/Type: Rice and Chestnut
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Post Fri. May. 09, 2008 8:24 am

Stoker or hand-fed that baby is begging for coal!

The flue pipe may have been reduced because oil burners require a very low draft to operate properly, around -.02" WC. You may have to convert it back, but that would be determined after the coal is burning. A stoker requires less draft then a hand fed.

The pressure gauge can be replaced with a combination pressure and temperature gauge. Another suggesting is to replace the temperature/pressure relief valve just as a precaution, unless you know it is fairly new and operates correctly. This will eliminate any fears of the boiler "exploding".

If you have all the parts for the grate assembly I'd try that first to make sure you want to switch to coal. You can always go the stoker route later.

I suspect that once that coal fire is going you will become a convert.
Heating a circa 1832 farmhouse with a Harman Magnafire Mark I & a 1959 EFM 350 (heating DHW).
100% Oil Free!
"It's what we learn after we think we know it all that counts."

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Richard S.
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Post Fri. May. 09, 2008 8:46 am

smrfld wrote: The front of my boiler is about 4 feet from the basement wall. Is that enough room for the stoker or can I put the stoker to the side and have that feeding tube at some kind of an angle? Either position would place the stoker conveniently beneath a basement window for easy loading!
The EFM's I believe can have the auger coming out the back or the sides, the others will have hopper. You'd have to make sure it will fit where you need it but that furnace you have now is so large I don't think you'll have any issues configuring any of them if you replaced it.

As far as wall clearance besides whatever the building specs are you'll want some room to get around it. Wherever there are any parts such as the auger mechanism you'll want access to that area and make sure you can disassemble it if you need too. If for example you get piece of rock in your coal you will need to take the tube and auger off to get it out. This is very easy to do as long as you have the room to do it.

If the window is next to where the furnace is you can run the auger right into the bin itself. Get a 55 gallon drum and put that inside the bin as well. If you get hopper design you will of course want an opening near wherever the hopper is. Personally I'd get one with the auger design, for one thing it's ground level as opposed to a hopper that is going to be pretty high, neither are you limited by the hopper size. Your hopper can be whatever you want to build it such as the 55 gallon drum. That's 400lb of coal.
Does the stoker work like an oil lamp -
A modern stoker boiler once set up properly is no different than any other heating appliance except you need to put col in the hopper and take the ashes out. Truthfully.
Last question .. what is the cost of a stoker? You are in PA, so pick-up isn't a big deal.
For a large boiler you're probably looking at start up costs around $6K+
"The difference between stupidity and genius is that genius has its limits."

- Albert Einstein

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LsFarm
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Stoker Coal Boiler: Axeman Anderson 260
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Location: Michigan

Post Fri. May. 09, 2008 12:38 pm

The idea to convert your boiler to a stoker is definitely something for a do-it-yourselfer. The stoker I showed photos of is from the late 1930's, or maybe mid 1940's. The company still exists as the Wil-Burt company.. To find a steam boiler craftsman who would be willing and able to convert a converted boiler from oil, back to coal will be virtually impossible.. so, you are going to have to do a lot of learning on the subject... And one big problem will be that there is virtually no new literature on converstions.. you will have to pursue old, antique 'collectable' literature for information.

So: lets start back at your first post, can you set out and photograph the grates, parts and pieces you have for your boiler.. lets first see if you actually have everything or almost everything you need to convert to a hand feed.. This I think is the most prudent first step.

As for the stoker,, I'm not saying it is even a functional idea.. with my conversion,, I was able to mount the stoker on a lift,and insert it into the combustion chamber ABOVE the ashpan, this allowed the ashpan to still function.. If you can't do this, then the removal of ash everyday will be a real pain. Probably making a stoker impractical.

Since you have a steam system, I have no clue how to piggy-back a modern coal-fired steam boiler onto an existing steam system. Something for an expert,, especially if you have a one-pipe system, that requires a constant drop for drain-back of the water in the pipes,, back to the boiler... so how to make it come back to the correct boiler?? I don't know..

More questions will for sure be coming.. I'd call around and see if there are any steam experts still practicing their trade.

Greg L
Burning Pea/Buckwheat through an antique stoker [semi retired SSboiler],
Running an Axeman-Anderson 260M boiler burning Pea, About 150-250#per day
Farming, Fixing, Fabricating and Flying: 'spare time' what's that?

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Rob R.
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Post Fri. May. 09, 2008 1:27 pm

Steam experts are a rarity, but they do exist.

Here is my story: My grandmother lives in a large home near Oneonta, NY that was built in the late 1800's. The house had some sort of huge converted boiler in the basement that fed the network of steam radiators for many gears. A few years ago it finally died and she had to find a replacement. No one would touch the system because it was steam, they all wanted her to convert to hot water baseboards. She finally called the Utica Boiler Company in Utica NY and they said no problem, within a week she had a new oil-fired steam boiler installed and running great.

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Sting
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Post Fri. May. 09, 2008 4:20 pm

steam is not that tough
**Broken Link(s) Removed**Like most things

it has its unique wants and needs
When you turn your boiler on -Does it return the favor?
I have finally lost my mind. Don't bother to return it. It wasn't working properly anyway!

David in Bayonne
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Post Fri. Jun. 13, 2008 6:44 pm

My first time on the board but I've been living with steam for three years now. I would think that as long as the water lines were set at the same height, and water level maintained to the more restricvted range boiler, that you wouldn't even need to separate the systems.

If the pipes that were set up by an artist throughout the house a century ago are working good order replacing the boiler is pretty straightforward- any plumber should be able to do the steam part. Make sure the steam side is done in black, not copper. Make sure your overpressure valve really works too- coal doesn't shut down as quick as oil. A steam system should work around 1-2 PSI in a normal house.

Spend thirty dollars and buy Dan Hollowhan's book. It is good.

Oh- my qualifications? Real estate broker in California years ago, aircraft mechanic, Attorney (honest to god, I was forty when I graduated) and researching replacing the boiler this summer. 1600 gallons a year. Unfortunately, Bayonne would throw a fit if I tried to put a coal boiler in here with tenants in the building.

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