The Basics of Hand Fed Coal Stove Operation
Listed here are the some of the basics for lighting, loading and operating a hand fed coal stove. Hopefully this proves to be useful for those researching coal as an alternative to traditional fuels for heating their home as well as a starting point for those lighting their first coal fire. Once the basic skill of starting and maintaining your coal fire has been mastered, there are many other threads on the forum discussing how to efficiently get the most heat out of an installation.
There are free standing and fireplace insert coal stoves available, the information that follows is applicable to both. These units are generally not connected to any heat distribution through the house, but rely on heat radiating from the stove, an air distribution blower or natural air flow around the stove to circulate the generated heat. Circulating the warmth from the immediate area around the stove to the rest of the house can be challenging and the ability to evenly heat the home is a reason some consider a coal furnace or coal boiler instead.Design:
Generally speaking a coal stove that has been designed to optimally burn coal will have a shaker grate system that the coal bed sits on. It will have vertical or near vertical sides lined with firebrick. It will have an ash pan area under the shaker grate and will have air controls on the ash pan door area to control the amount of combustion air getting to the coal bed. Coal fires need to have their combustion air come up through the coal bed (primary air). Some stove designs include a thermostatically controlled damper in the ash pan compartment to automatically adjust volume/amount of combustion air based on the stove temperature. Minimal over fire (secondary) air can be useful to maximize burn efficiency, but too much over fire air and the coal bed may not burn correctly and may go out. Too much over fire air is a common mistake made as people transition from burning wood to coal and results in frustration trying to keep a coal fire from going out.Chimney:
The hand fed stove is connected via a flue pipe to a chimney. A hand fed stove CANNOT
be power vented. Risk of CO poisoning due to a loss of power causing the power vent to be inoperable while the hand fed coal stove continues to burn is the very important reason why. A masonry chimney with a tile flue liner is the best long term construction. The appropriate size of the flue is determined by the stove manufacturer. Class A stainless steel chimneys are available but they are known to corrode at some point. Stainless steel liners in a tile lined chimney are not necessary. Unlike a wood stove, coal does not produce creosote so there is no danger of chimney fires. Coal will produce fly ash that needs to be periodically cleaned. The fly ash will mostly accumulate in horizontal sections of flue pipe. It is best to check these sections periodically and clean as necessary. It should be checked based on amount of coal burned (e.g. every ton) rather than by a time period (e.g. every three months). Vertical sections tend to remain clear, but your specific installation should be checked to verify this is so.Other Items:
It is imperative that anyone that has an appliance in their home which burns a fuel install Carbon Monoxide monitors or alarms for safety. Coal stoves are no more or less likely to cause CO issues than any other appliance (including water heaters, furnaces, boilers, kerosene space heaters, vented or ventless propane heaters etc.) burning a fuel (oil, natural gas or propane). A CO monitor will have a numeric display with the ability to show low levels of CO before reaching their alarm setpoint. Seeing this number before the alarm point is an early warning to take action. CO alarms will not have a display but will alarm when the CO detector reaches its setpoint. Both monitors and alarms need to be replaced periodically, check the packaging for recommended intervals.
When operating a coal stove it is useful to have a couple temperature gauges, one for the stove body and one for the flue pipe. Temperature changes on the stove can be observed as primary air settings are adjusted.
Most coal stove installations have either a Barometric Damper or a Manual Pipe Damper installed on the flue pipe to help optimize the operation of the stove. A barometric damper automatically adjusts based on pressure changes in the flue pipe while a manual pipe damper is adjusted by hand. The merits of each are detailed and debated in a few threads on the forum and can be further researched there. Each stove / chimney installation has its own ‘personality’ and may or may not benefit from using either of these items.
It is also very useful to have a manometer which is a gauge to measure draft. The manometer can be used to verify effects of adjustments to the primary air. It can also be used to accurately set the counter weight on a barometric damper if that is used on an installation. If the manometer is permanently installed it can be used as an early warning indicator that the draft is weakening which could be due to warm weather effects or that flue pipe cleaning is needed. Corrective action can be taken before exhaust gasses find their way into the home.Lighting a Coal Stove:
Anthracite coal needs to have an established wood or charcoal fire and be added slowly when you first start your stove. Here is a link to a video showing an effective method to start a coal fire in a hand fed coal stove.Quick Start Method Video
Some prefer to use charcoal rather than kindling and wood, but the idea is the same. You get an established fire with your starter fuel of choice and gradually add the coal in layers. As the coal catches keep adding layers until it is filled to the top of the firebrick. A common mistake by new coal burners is to think that less coal means a smaller fire like with wood burning. However the size of the fire is controlled by the amount of combustion air, not by the amount of fuel in the firebox. In fact less coal in the firebox may mean the grates are not completely covered and combustion air would bypass the coal bed and the coal fire will go out. The full firebox means you will get longer burn times between necessary stove tending, not necessarily more heat.Operating a Coal Stove:
Once the coal stove fire has been started, the coal bed established and the fire box filled it is time to monitor the temperature of the house and temperature gauges on the stove along with the manometer reading for various weather conditions and adjust the primary air as necessary. The appropriate primary air setting is dependent on the stove design, chimney draft characteristics, insulation level of the house and personal comfort preferences. There is no single air setting answer that applies to all installations. Use the forum search function to find threads detailing your stove model and use the experience of others as a starting point for your settings. A little experimentation and adjustment will get it dialed in for your specific installation. Any adjustment that is made should be given about an hour to see the effect.
Once the temperature has been ‘dialed in’ there is little to no adjustment necessary between tending the stove if weather conditions remain steady and that is one of the appealing features of using a coal stove. Changes in temperature or wind may have an effect and some adjustment to primary / secondary air or damper settings may be needed to optimize the efficiency of burning that load of coal. You will soon learn the characteristics of your stove and installation for different weather conditions.
Some have found that maintain a log book of previously discovered settings is very helpful for future reference.Reloading a Coal Stove:
After a coal stove has been burning for a period of time it will need to be ‘tended’, ash shaken and coal added, which takes about ten minutes. Different stove designs will vary but generally 8 to 12 hours between tending is common in cold weather. During milder weather 24 hours between tending is not uncommon for some stoves. While specifics may vary slightly the general process for successful tending involves ‘livening’ up the fire for a few moments by providing more primary air, then shaking down the ashes until they are cleared and then adding coal to the firebox.
In order to liven up the fire, some coal burners will open the primary air control all the way, some will open up the ash door itself for a few minutes. It is very important to not leave the stove unattended while in this mode as it does not take more than a few minutes for the stove to over fire when air is supplied in this manner. It is a good idea to set a timer or alarm for 10 minutes as a reminder that the primary air is wide open. When you see vigorous blue flames coming up through the coal bed, reset the primary air control to its normal setting or close the ash door since leaving these open could allow fly ash dust out of the ash pan area as you are shaking.
Shake down the stove rigorously clearing the ash until you see an even glow from the coal embers across the entire grate area. It is alright if some embers drop into the ash pan from areas that clear more quickly. Shaker controls vary from stove to stove but usually short choppy motion is better to only allow ash through the grates and to avoid having large unburned pieces of coal jam the grates.
When you are done shaking, open the primary air controls or ash door again and add coal to the firebox area. As you are adding coal, leave an area of the coal bed exposed that has blue flames present. This is very important because the new coal will give off volatile gas as it heats up. If a flame is present, this gas will burn off harmlessly, evidenced by blue flames dancing across the new coal. Additional secondary air will help maintain the flames for burning off these volatiles. If a flame is not present and the gas builds up in the firebox without being burned off it can ignite and cause a ‘puff back’ when a flame does become present. Once again, do not leave the stove unattended during this time period, usually about 5 minutes at most. When consistent blue flames are present on the new coal bed, reset the primary and secondary air controls to the normal operating level (or close the ash pan door). You are now ready to enjoy the heat and come back in 8 – 12 – 24 hours and do it again.Ash Pan:
The ash pan will need to be emptied about once per day. It is important to not let the ash pile up in the pan so that it is against the bottom side of the grates. Besides impeding the combustion air flow it will also cause the grates to overheat and possibly warp causing damage requiring replacement. Some coal burners employ two ash pans pulling the full one out after shaking down and replacing with an empty one. The full pan sits next to the stove cooling before taking it outside to dump into a metal ash container. Others will use one ash pan. Some people use the ash as anti-skid material in winter on their driveways, some use it to fill potholes in gravel driveways, some mix it with soil and use it as fill for low spots in yards and some bag it and put it in the trash or take it to the dump.