Coal Stove choices, installation, operation, & safety:

This article discusses the isntallation and operation of coal stoves used as heating appliances in buildings. We include details about heat output control and draft regulation.

The article links to additional details providing coal stove fire cleareances, chimney safety and coal stove sources, repairs, fuel costs, & related research.

Coal Stove Dampers & Draft Control

Coal fueled heaters use manual dampers in the coal stove flue or for larger and automatically-fed coal fired boilers or furnaces the system may incorporate a thermostatically-operated automatic flue damper to control both draft and thus the system's heat output.

The coal stove shown above was installed by the author (DF) in the 1970's.

A slider along the stove bottom permitted the user to adjust the air intake rate - a necessary combustion and heat control since the installation of this stove in front of a small fireplace gave no access room for a flue damper control.

The second fireplace-inserted heater shown below is a coal stove that was designed to also burn wood.

This wood/coal heater, installed by Paul Galow in Poughkeepise New York in the 1970's, also had a sliding air intake control and no accessible flue damper.

The vertical lines you see in the glass front of each of these coal burners allowed the installation of glass that would not fracture due to thermal expansion, allowing the occupants to enjoy watching the fire. Yes ultimately these get broken by a careless occupant or user, putting the stove out of use until the glass could be replaced.

Watch out: if the incoming combustion air cannot be shut down because of leaky coal stove gaskets or other damage like the broken glass in the coalstove door, the coal stove is unsafe as its burn-rate cannot be regulated.

See CHIMNEY FIRE ACTION / PREVENTION

Also see FIRE CLEARANCES WOOD & COAL STOVES

Can I put two barometric dampers on the same flue along with a manual one on my Alaska Channing III Coal Stove?

I have a Alaska channing 111. My barometric damper is 6 in then [the flue vent connector goes to 8 in to connect ] to massonary chimney.

It seems I need two dampers. I installed a manual damper to help

My question is can I put 2 barometric dampers in the same flue to control proper draft (Dec 14, 2014) Bill

Reply: adding a second damper to increase or redude draft at a coal stove or woodstove isn't the right solution

Bill

The Alaska Channing III is a coal stove (shown at left) designed to burn rice coal and with a BTUh output of 5,000 to 85,000 BTUh. That heat output capacity is controlled in part by controlling the fire rate by controllinb combustion air.

Heat control for this coal stove is provided either by a manual control to adjust heat output (basically you're adjusting the input air flow rate), or by a wall-mounted thermostat system that operates in two heat output ranges (low fire and high fire).

As long as the single barometric damper is properly adjusted and capable of opening to permit enough air intake to keep the draft at the desired level it should work just fine.

The volume of air leakage past a barometric damper in a flue isn't significant in stove operation, so in my experience and opinion if you are trying to reduce the draft seen by your coalstove, adding a second damper would have little effect should the first damper already be fully closed, and it would have absolutely no effect if you're trying to increase the draft.

If the damper were not capable, such as in an area of very high winds creating unusual drafts over a chimney top, the solution would probably include a better chimney cap that gives protection against downdrafts.

Watch out: If you mean by your question that you are getting too much heat or that the coal stove seems to be overheating, this condition can be unsafe and in fact in extreme cases (such as leaving the coal stove door ajar with a fire burning) you can warp and ruin the stove or even cause a house fire.

Watch out: Where I was getting too much heat out of a wood or coal stove for the living space involved, I found that running the stove at its slowest setting (least draft) helped, but when burning wood it could speed the deposit of creosote in the flue and chimney, risking a dangerous chimney fire if those components were not kept clean.

Ultimately where one of my woodstove installations was just putting out too much heat for the occupied space, I traded it to Paul Galow for a wristwatch. You can see that stove

at WOOD STOVE OPERATION & SAFETY 

Bottom line: It should not be necessary to install two barometric dampers on a heating appliance unless you are facing very unusual draft control problems. Nothing I read about this coal stove suggests that it would suffer from excessive draft.

In fact the company notes that power vents can be used with their equipment (creating a still-stronger draft) and that some models including the Channing III rear vent can be direct-vented (with no chimney).

Installing 2 dampers is not something I'd recommend as adjusting them would probably be difficult, adding complexity that should not be necessary. It's like adding complexity to try to solve a problem rather than understanding the problem first.

Coal Stove Installation Details & Overheating Warnings

Some of the text below is excerpted from Channing's coal stove installation manual - as indicated. Other advice from the US DEHW is cited as well.

The coal stove shown in our drawing, popularly called a"pot belly stove" and also a "Cannon stove" was a cast iron coal burning space heater widely used from the late 1800s through at least 1955 in the U.S. This stove could burn both wood and coal.

Our drawing shows that primary combustion air entered at the ash door to feed the combustion of coal or wood. Secondary combustion air also entered through smaller openings in the feed door.

As the coal or wood burned it produced additional combustible gasses that also burned, radiating heat through the cast iron into the occupied space.

Exhaust gases were vented through the exhaust flue to the building exterior, usually through a masonry or metal chimney.

In the coal or wood burning stoves that we (DF & PG) completed, in addition to draft controls at the stove itself we usually included a draft control in the exhaust flue above the stove.

Illustration: a Cannon stove or coal stove, adapted from Basic Housing Inspection, US DHEW.

• Coal Stove Installation & Safety:
  
  Check that you have installed the stove according to the company's instructions. In most jurisdictions installing a coal stove requires a building permit, safety inspections, and of course compliance with combustion clearance and other safety guidelines.
  
  Our 1950s US DEHW housing inspection manual warned:
  
  Where coal space heaters are located, a floor protection should be provided. This would be a metal covered asbestos board or a similar durable insulation material. One reason for the floor protection would be to allow cooling off of hot coals and ashes if they drop out while ashes are being removed from the ash chamber.
  
  Walls and ceilings of a combustible construction exposed to furnace [sic] radiation should be installed, and the following clearances are recommended:
  
  Space heaters - a top or ceiling clearance of 36 inches, a wall clearance of 18 inches, and a smoke pipe clearance of 18 inches. - (US DEHW 1955)
• Coal Stove Fuel:
  
  Check that you are burning only the fuel recommended by the manufaturer.
• Your Channing III coal stove is designed to burn only pea-coal. If you are burning wood pellets the result is dangerous: a hopper fire. (The company does have a different stove model that can burn wood pellets).

• Coal Stove Operation & Openings:
  
  Check that the coal stove door or other openings are properly closed and that all gaskets are in place and not leaking.
  
  If you set combustion air inlet control(s) to their most-closed position and the stove fire does not slow accordingly then it's likely that there are air leaks into the stove and it should not be used.

Here is an antique Dubuque coal burning stove poster (for sale at redbubble.com).

We pose that the Dubueque coal burner was produced by the Dubuque Steam Heat Company, founded in in 1879 in Dubuque, Iowa.

• Coal Stove Heat Controls:
  
  Check that you have properly set the manual or thermostatically-controlled thermostat to control the heat output of the coal stove and confirm that the heat control is working.
  
  This means turn the heat control to its lowest setting. The fire should get very low or small. To completely turn off the a stove that uses a power vent it may also be necessary to un-plug or turn off the vent fan.
  • If you are using the manual thermostat (the "Auto Heat Control Box") and you set temperature down check that indeed the coal fire slows (air input is reduced).
  • If you are using the wall-mounted room thermostat system check that the air damper on the stove is responding to changes called for by the thermostat.
• Chimney connection for coal stove:
  
  You cannot safely share a chimney flue to which a coal stove is connected with other heating appliances. Doing so risks dangerous fire spread, carbon monoxide hazards, backdrafting and other operating problems as well as of course building code violations.
  
  Be sure that a properly designed chimney cap is on the top of the flue
• Coal Stove Draft Regulation:
  
  Install a single barometric damper on the larger diameter flue section as the company recommends.
  
  The company does recommend the use of a barometric damper on the Alaska Channing III when it is connected to a chimney to overcome excess draft caused by site conditions such as wind, outdoor temperature changes and changes in barometric pressure (the least of these forces).
  
  Regulating the draft gives more complete combustion, more even heat output, and more efficient use of your coal fuel.

To obtain an installation & operation manual for your Alaska Channing III coal stove, contact the company at the link or telephone we give at the end of this article.

Watch out: if the flue damper rusts or becomes damage it may be impossible to slow the chimney draft, resulting in an over-heating stove and possibly a chimney or house fire. Though questionable fire clearances and accumulated creosote may have been factors, just such a runaway wood stove fire and its disastrous results are illustrated

at CHIMNEY FIRES & WOOD STOVE SAFETY

Coal Stove Combustion Properties

Shown here: The Acme Giant Pot Belly Stove, (ca 1890 - 1910) sold widely through Sears & Roebuck, appears to be a close match for the coal/wood stove drawing used in our 1950's DEHW basic housing manual and illustrated above on this page.

Around 1900, the Acme Giant, produced by the Newark Ohio foundry, sold for $4.95 in the U.S. [Advertisement image on Pinterest]

Acme stove models included at least the Acme Sunburst and the Acme Ventiduct, sold by Sears as the Acme Cannon Heating Stove, the Acme Giant coal stove, and similarly named stoves.

We think that the Newark Ohio Foundry referred to in this advertisement was most likely a foundry operated by the Moser-Wehrle Company, founded in Newark Ohio in 1883.

Moser-Wherle produced stoves sold by Sears under the Acme Brand as you can see in this Sears Acme Stove Instruction Manual. [Image]

The Licking County Historical Society notes that by 1907 the foundry, located near Wilson & Union Street produced about 190 cast iron stoves a day.

A more ornate version of this stove, the Acme Ventiduct, restored [Image] is offered for sale for close to $4000. (at goodtimestove.com).

Excerpts from Basic Housing Inspection cited below:

Space Heaters

Space unit heaters are the least desirable from the viewpoint of fire safety and housing inspection. All unit heaters must be flue connected.

Coal-Fired Space Heaters

Cannon stove - this is illustrated in Figure 13 and is made entirely of cast iron. In operation, coal on the grates receives its primary air for combustion through the grates from the ash door intake.

Combustible gases driven from the coal by heat burn in the barrel of the stove, where they received [sic] additional or secondary air through the feed door.

Side and top of the stove absorb the heat of combustion and radiate it to the surrounding space. - BHI, DEHW p. 104

1. About 12 pounds of air is required for complete combustion of 1 pound of hard coal.
2. Approximately 5 pounds of hard coal is consumed per hour for each square foot of grate area.
3. Approximately 12 inches of fire bed will heat most efficiently
4. Anthracite coal burns more slowly than soft coal, is cleaner to handle - hence more widely used.
5. Large-size coal does not compact - hence the air spaces are too great and allow gases to escape into the flue unburned.
   
   Small size coal compacts too much and inhibits airflow through the coal to allow for good combustion [sic].
   
   Mixing of coal size is recommended, i.e. stove and chestnut.
6. Fires burn best when the weather is clear and cold, because of reduced atmosphereic pressure on the air in the flue - hence greater draft velocity.
   
   During periods of heavy atmosphere or rainy weather the temperature of flue gases must exceed normal temperatures to overcome the heavier atmospheric weight.
7. During extreme cold weather, coal should be added to a fire once in approximately 8 hours; moderate weather - 12 hours. - DEHW, BHI, p. 105, op. cit.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Axeman Anderson M260 coal boiler troubleshooting

Help! Have a furnace problem. I have an Axeman Anderson M260 coal boiler. I can't get it to work right.

The only way I can get heat is if I plug it in. And the only thing that controls is the motor and the auger, and the shaker arm to shake out the ashes.

Running it this way I control the heat. When the house gets to the desired temperature I unplug it.

What I was wondering is if the Triple Aquastat relay would cause this problem. There is only one zone this controls. Any help would be greatly appreciated. (Nov 6, 2014) Jennifer C.

Reply: where to find help with an Axeman Anderson Coal Fired Boiler

I'm confused. How would the coal-fired boiler be expected to work if its coal feeding augur were not working - it'd have no fuel. Axeman's current coal fired boiler, the Anthratube, is described as fully automatic. Here is a copy of the boiler instructions

www.axeman-anderson.com/pdf/anthratube.pdf

Perhaps you're saying that the aquastat should be controlling the coal feed and it's not?

Tell me the model of the aquastat and perhaps we can comment on that control.

To contact Axeman for help:

Axeman-Anderson, Company
300 East Mountain Avenue
South Williamsport, PA 17702
ph. 570-326-9114
fx. 326-2152
email: info@axeman-anderson.com

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Continue reading at FIRE CLEARANCES, WOOD COAL & PELLET STOVES or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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