How To Clean A Efm Coal Stoker

Newsome Fornoth · Wednesday, December 1, 2021

The first part of this post deals with anthracite coal if you're not in the Northeastern part of the U.S. you may want to move onto the section at the end regarding bituminous coal usage.

The Basics

Typically for those that are inexperienced with coal the first thing they think of is some sweaty guy in the depths of hell shoveling coal into some medieval looking monstrosity. They think of billowing black smoke, dirt and dust etc. That's not the case with anthracite coal and a "modern" stoker. Modern is in quotes because these designs have been around for more than half a century.

Bituminous coal found in Western Pennsylvania and just about every other state in the U.S. can resemble that description, it does produce a lot of smoke, soot and a powerful sulfury odor. What I'm discussing here is anthracite coal which is the highest rank of coal. It's nearly 100% carbon and does not contain the impurities found in bituminous coal. On the North American continent its only mined in Northeastern Pennsylvania (NEPA), there are only a few other places in the world this type of coal is found. It's primary use is for heating purposes unlike bituminous which is used to generate electricity in power plants. It's also used as a medium for water filtration among other things. It burns with a bright bluish flame without any smoke or soot and you'll never smell it inside or outside your home unless you get close to the top of your chimney. This makes it an ideal fuel for residential or commercial heating even in an urban environment.

That's not to say its perfectly clean, there is some dust involved with moving the ashes and the coal but this can for the most part be eliminated with caution and taking a few minor steps like dampening the coal before moving it. Isolation of a large boiler eliminates the dust problem all together. Smaller stokers meant for being installed inside the living space will be the most problematic. Overall from the consensus I gather from my forum members that have used wood or wood pellets in the past its not any more dirty that using either of those.

Environmentally speaking the CO2 emissions are slightly greater than even bituminous coal in a laboratory environment however unlike bituminous coal other emissions are very low and rival those of oil and gas and in some cases are below them. I'm just mentioning this for the benefit of those that are environmentally conscious (although I think you're nuts ) because I don't want to give the impression that it does not produce CO2 when I say it burns cleanly. That's really for another debate anyway and there are many other factors involved other than raw laboratory data.

The Costs and Availability

This and where you will purchase anthracite should be the first thing you should investigate. If you're in the Northeastern U.S. then you're in luck because most likely there is dealer in your area. The farther you get away from NEPA the more it costs. The cost per ton currently can range from $130 per ton in bulk in NEPA up to about $350 for bagged coal in other states like Maine. Comparing to other common fuels here's a breakdown:

Coal
- @$160 per ton delivered in bulk = $7.55 per million BTU
- @$300 per ton bagged = $14.17 per million BTU

Wood Pellets
- @$300 per ton bagged = $22.73 per million BTU

Wood
- @$200 per cord = $15.15 per million BTU

Fuel Oil
- @$3 per gallon = $27.73 per million BTU

Note that these are typical prices and you will have to take into account what the cost is locally for you. You can do your own comparisons for the fuels above and others like natural gas and electric using this calculator provided by the DOE: Fuel Cost comparison Calculator

Note that the efficiency value for coal is not correct on this calculator. The typical efficiency of coal unit is more likely in the 80% range with some units achieving upwards of 90%. You will need to adjust that value to at least 80%. Truthfully they cannot make them anymore efficient because you do need some heat going out the chimney to maintain a draft. The document is an Excel spreadsheet, if you do not have Excel you can download Open Office for free to open and use it.

Coal Burning Stokers

You may be surprised to learn coal is quite easy to manage and use, that's one of the benefits. There's two distinct types of units, stokers and hand fired stove. Stokers are the most popular type because these are automatic. They are not much different than any conventional heating system, they are thermostatically controlled. Hand fired units are quite popular too and would be more like using a wood stove and requires manual adjustments. Each has their advantages and disadvantages.

The stokers internally pretty much haven't changed in years, they are time tested designs that work. If you're familiar with a pellet stove these would be similar to them except in production for much longer. Some designs have been around for more than half a century.

There are three basic designs used in stoker units. One type auger fed with a firepot, there is the anthratube design and lastly the most common in smaller stokers the bed design. They all rely on the same principle, they force air through the coal. This is the boiler that's been in our basement for 25 years, it will be there for at least another 25. They are that durable.

As you can see other than the two doors on the front it looks no different than most furnaces. This boiler uses an auger and firepot design, It's the Cadillac of coal furnaces. You'll notice the wood bin behind it, not shown in this picture is the auger. This is a pipe that comes out of the furnace into the bin. Inside the pipe is an auger that feeds the coal into the firepot inside the stove.

Here is newly assembled firepot for an EFM:

Note the holes inside the pot, this is where air is forced through to make the coal combust. Stokers do not rely on a natural draft. The pipe sized opening on the lower left is where the coal would enter via the auger. It feeds up from the bottom of the pot, as more coal is fed the ashes spill over the sides into ash can below. Basically all you need to do is put coal in one side and take the ashes out of the other. You can find a complete pictorial of the EFM assembly from start to finish by here:

Pictorial of all DF520 Stoker Parts and Assemblies - e-f-m Heating (http://nepacrossroads.com/about2916.html - broken link)

Axeman-Anderson and AHS make another type based on the athratube design which was part of a study, this is the one that can achieve the highest efficiency. It was introduced after WW2 in part in an attempt to help save the anthracite industry. This too employs an auger feed but may also use a hopper design.

Bureau of Mines Report 4936 Axeman-Andersen Antratube Boiler - Coal Stokers: Boilers, Furnaces and Stoves

Lastly there is the bed type, these use a hopper on the side of the furnace or the stove. They are used in both large boilers and the more common smaller hot air stokers. This is a smaller Keystoker made for supplementary heat. These typically are 90KBTU though and can provide most of the heat in a 2000 sq ft. home providing you get it to circulate well, Note that there is a hopper on the back which is not pictured you fill with coal:

They also make a large boiler with a hopper design:.

This what the bed looks like inside the stove, the coal is pushed from the back with a pusher block and off the end into an ash pan:

A stoker is thermostatically controlled. They will ramp up or down depending on the demand for heat. It's no different than any other furnace except for the little bit of work. Typically during the coldest days of the winter you will need to add coal about every 2 days and take the ashes out. Overall not more than few minutes each day to keep it going. Larger boilers can go longer and if you take the time to plan ahead you greatly reduce the work involved by creating a self feeding bin.

Hand Fired Coal Stoves

Hand fired stoves as already mentioned are very similar to a wood stove. They use a shaker grate system. These typically need to be attended too once every 12 hours when outputting a decent amount of heat however they can burn past the 24 hour mark if not being heavily fired, in comparison a wood stove needs to be refueled every 4 or 5 hours. The benefit of having a stove like this is they don't need electricity to run. If the power goes out in your area frequently this would be an ideal solution. Here's a picture of shaker grate, this is from a unit EFM will be reintroducing:

This grate sits in the bottom of a firebox, twice a day you will need to shake the coal down to get rid of the ashes and add new coal. The combustion is controlled via the draft, you can turn the heat up or down by adjusting the amount of air. These are not like stokers with on demand heat. If for example you put more air on the coal it will take up a length of time to ramp up. Turning it back down takes even longer. Most people find an appropriate setting and just leave it there and do their twice a day routine shaking down the ashes and adding more coal.

Most of the hand fired stoves are smaller and meant for supplementary heat but again they have a very high BTU output and can provide most of the heat especially in a smaller home. BTU's will vary by model. Larger hand fired boilers are pretty rare but they do exist. Harman makes one and EFM is reintroducing a model that they stopped production on nearly 30 years ago because of the demand for them . Here's some pictures of the prototype. Note that the insulated jacket that will come with the production model is not pictured. This unit will also be able to burn wood, note it will be meant to burn dry hardwood. It's not the same as Outdoor Wood bolier that can burn any type of wood:

There are other wood/coal hand fired combos available.

Maintenance of Coal Fired Appliance

The maintenance on either a hand fired stove or boiler is pretty limited. The biggest part is cleaning the flue. When you burn coal fly ash will accumulate inside the flue on any horizontal plane and in the bottom of your chimney. If you do not clean this out it the flue pipe will eventually get blocked and flue gases will back up into your house.

For larger boilers this is usually a once a year chore and may take an hour or longer. Ours has an enormous flue pipe and a lot of room in the chimney cleanout and could probably go at least 3 years. Ours is trivial to clean because of the way we set it up. No more than a few minutes because the flue pipe does not have to be removed from the furnace. How often you need to do this will vary by manufacturer, the smaller stokers are usually recommended to be cleaned out once a month because they have lower tolerances than the larger boilers. It will vary and you can adjust your schedule as needed, most people find they can get by through the season but it's very important that you determine exactly how long you can go.

Other maintenance will be cleaning it out if you shut it down for the warmer weather, yo don't have to do this but you will extend the life of the unit by doing it. Fly ash is corrosive when it mixes with damp air. On the boilers and stokers there is other minor maintenance that has to be performed occasionally like putting a few drops of oil on the motors but overall its only an hour at most per year.

Hot Water Coils

Another benefit of a coal fired stoker/stove is the Domestic Hot Water coil which can be purchased separately. This can provide all you domestic hot water on the larger boilers or may be simple short loop that goes through the smaller units. We run our large boiler year round for this reason. From about mid May until September we burn about 1 ton of coal. This provides us with domestic hot water. It's on par with using other fuels if not cheaper during this time of the year. During the winter its practically free. This continuous burning will also prolong the life of a large boiler significantly and cuts down on maintenance costs.

Atypical setup such as ours still uses hot water heater but with a thermal siphon loop. The hot water naturally circulates from the coil inside the furnace into the hot water heater continually replenishing the lost heat. The hot water heater rarely ever comes on, its not much more than a glorified storage tank. The other benefit of this setup is endless hot water and the hot water heater acts as a buffer between the scalding hot water produced by the coil. The boiler is fully insulated and is so efficient stack temperatures are minimal so heat going into the basement during the summer is minimal.

The coil in our boiler can provide enough hot water on its own, on smaller units the coil is much shorter and supplements the heating hot water through the thermal siphoning action.

What if I need to go away for a week?

Obviously you need to be around especially with hand fired stove but in that case you'll be using it for supplementary heat. The boilers on the other hand are intended to be full house systems but there are options and things you can do to solve this problem.

Firstly most people are buying boilers to replace existing heating systems. If you have the room you can leave you existing heating in place for a backup system. There are many ways to accomplish this but I'm not going to go into detail here. This is really the ideal solution as you will have two independent heating systems and is what I recommend is the best path.

Another option is both Keystoker and EFM the leading boiler manufacturers offer a add on oil gun option. This can be used instead of the coal, it's not a flip of the switch conversion from coal to oil but overall it's not that much of project. The oil gun is intended for just this purpose, they are not made to be oil boilers and will not have the efficiency of oil boiler when using oil.

Lastly through proper planning and under the right circumstances you can increase the burn time a great deal. The auger fed designs are ideal for this as the auger is at ground level. The first thing to consider is where you will palce your coal bin and how to configure it. By this I mean create a bin that is a hopper itself. you will need a very high ceiling to accomplish this. All the coal feeds onto the auger so we no longer have to worry abut supplying fuel. That leaves the ash capacity, if you build the boiler on top of few courses of block you'll increase the capacity. Using both of those suggestions you can easily have coal boiler that can burn unattended for more than a week even in the coldest weather. Also note some people have made automatic ash removal systems similar to the auger that feeds the coal but that would really only be practical in really large houses or commercial buildings.

Ashes, What to do with them

This really comes down to where you live. In my town there is lot of people that utilize coal so they pick them up. It's actually a benefit for them because they can mix them with the salt for winter road maintenance. In places where they are not picked up the can be put pout with the trash but understand there will be a lot of them. The people that pick waste up in this area will usually provide a yearly fee for doing it.

If you're in rural are it's considered clean fill and they can be used for that purpose. If you want to make use of them for other purposes like mixing them with concrete for sidewalks they excel for that or even if you wanted to use them for "Dirtcrete".

How to dispose of the really depends on your situation.

Contolling Dirt and dust

Anthracite is extensively cleaned before it reaches the consumer. For a proper burn it has to be sized correctly, during this process dust and dirt is eliminated as much as possible. Anthracite has a glass like composition, once fully clean it will actually not dirty your hands if you handle it.

That's not to say it's completely dust free as dust is created everytime its moved through breakage, Some simple methods for controlling the dust inside the home is to lightly dampen it with water before moving it. If you're buying in bags it will most likely already be damp. It can also be purchased with a light coating of vegetable oil.

Overall from the consensus I gather from others that have used wood or pellets it's no more dirty that either of those.

Where to get the coal

The coal itself can be purchased directly from the processing plant in bulk for a significant amount of savings or you can have it delivered if you're in the NEPA area. Once outside of the NEPA options become smaller but there are dealers across the Northeastern part of the U.S. that carry it in 40lb bags and in some cases bulk. Generally speaking bulk is a lot cheaper than bagged especially in NEPA.

If you're in rural setting and outside the NEPA area and have the room you can save yourself a bundle by getting a whole trailer load. Sounds to be bit over the top but you can save upwards of $100 per ton which equates to roughly $2200 on a tractor trailer load.

How much coal will I need

A typical 2000 sq. foot home will use about 4 to 5 tons a year but this really depends on your particular circumstances and habits. The same house with 6 inch walls and new windows can use as little as 2 or 3 tons in year. 1 ton of coal will produce about 25 million BTU's .

Where can I store it?

The coal can be stored anywhere forever, either inside your house, outside etc. You can dump it on the ground and leave it there for 20 years and use it then. It may lose some oomph over those years but its not much. Moisture has no effect on it even when you go to burn it.

Cost of the Stove/Furnace

You can spend as little as $1500 or much less if you can find a used one. On the high end the boilers start at about $5000 which will heat a 3000 sq. ft. home and from there the sky is the limit. Keep in mind that although the expense for a large boiler is quite a bit these can run forever. Typical replacement of pumps and motors aside you will most likely not have to replace anything for decades. They are all well built machines, boilers that have lasted 50 years with proper maintenance are not uncommon. The lifespan of smaller stokers and hand fired stoves is shorter but you can expect at least two decades from one.

Here's some links to the major manufacturers of stokers and stoves in Pennsylvania:

Leisure Line Coal Stoves - Automatic Coal Stoker Stove Home Heating Systems

efm Heating - Coal Heat - AF Coal Heater / Coal Furnace (http://www.efmheating.com/stokerfiredfurnace.html - broken link)
Keystoker
AHS Coal Stoker Boilers
Axeman-Anderson - Anthratube Coal Boiler
Alaska Stove - Home (http://www.alaskastove.com/cms/ - broken link)
Harman Stove Company
Reading Stove

Each of these companies make an outstanding product. You will not be disappointed in any of them, which one to to look at really depends on your needs and budget and other considerations.

But the cost of the coal will go up if everyone buys one of these.

That may be true to some extent especially in outlying areas but at this point locally in NEPA it's even cheaper than wood if you're paying market value for the wood and its most definitely easier to use. Costs have risen a little recently but this is due to increased costs for diesel fuel and other energy costs used to produce and move it. Anthracite Coal historically has not been subject to the wild fluctuations in price such as other fuels. For the last few decades you generally have a modest price increase in the fall and generally you'll also have a slight decrease in the spring. Adjusted for inflation according to my records going back to the 80's the average cost per ton is actually a few dollars less now. As a recent example anthracite at the breaker was the same cost from the Fall of 2007 until about mid August 2008 while other fuels rose in cost dramatically.

Using bituminous coal

I do not know a lot about bituminous usgae but there are many on my forum that do, check there for more info. What I do know is that it is not as widely used for home heating because it poses some distinct issues for residential heating. Firstly bituminous burns with a sooty black smoke and does produce a strong sulfury odor when burned which pretty much prevents its usage in an urban environment. How much will vary according to the coal, the content of impurities and volatile matter that cause these issues varies from the source of the coal in different parts of the countries. Some bituminous coals are quite suitable while others may not be.

The other issue is when burned bituminous coal can form what is called a clinker. A clinker is a fused mass of material that can be hard as rock which makes the use of a stoker stove impractical in many areas but EFM does have a working prototype bituminous stoker suitable for some bituminous coal. These clinkers can cause problems in hand fired stoves as well for obvious reasons.

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In conclusion there is one more benefit. This coal is a product of the USA as well as the stoves and stokers themselves. The money you spend on the fuel or on purchasing one of these units stays right here.

If you have any questions post them and I'll try to answer them. For those of you that wish to investigate this more there's a wealth of information on my forum and plenty of people willing to give a hand:

Anthracite & Bituminous Coal Forum