Introduction to Coal Burning for People Starting Research into Alternative Fuels....
With the rising cost of traditional fuels (oil / propane) many are looking at alternative fuels as sources of heat. If you are in an area that is able to source either anthracite coal or bituminous coal competitively priced to the traditional fuels this may be a viable alternative for you.
This introduction is for people that are exploring coal as an alternative fuel. Detailed information can be found in the many threads on the forum discussing general or specific installation related questions. Keep in mind, coal burning is a hands on operation, requiring more effort than turning a thermostat and is not for everyone. The savings that can be realized by using coal, while it can be substantial, is simply not worth the effort for some people.
Burning coal for fuel can be as clean or as dusty as you make it. Careful handling of the coal can minimize the coal dust and careful handling of the ash pan can minimize the fly ash. The stories of dirty coal burning are greatly exaggerated and can be easily controlled with little effort. As with any appliance that has a flame a couple CO monitors / alarms must be installed for safety. Also highly recommended is a manometer which is a gauge that measures draft. It can be used to set and optimize combustion air settings on the coal burning appliance as well as an early indicator of maintenance issues. Temperature gauges are also recommended to monitor stove and stack temperatures.
Coal can be burned in a few different styles of appliances that can be categorized as either hand fed or stoker. The BTU capacity of the hand fed stoves are generally 50K to 100K BTU’s although some models are outside this range. The stoker stoves can generally range from 10K – 100K BTU’s (some are larger) while the stoker furnaces and boilers are sized to supply from 100K BTU’s and up depending on the heat load of the structure.
The hand fed stove has the coal loaded into the firebox (or a hopper that gravity feeds into the firebox) by shovel or bucket generally a couple times per day (similar to a woodstove). The hand fed coal stove will have shaker grates to clear the ash from the firebox and an ash pan area below the grates. Most all of the combustion air for burning coal must come from the ash pan area up through the grates and through the coal bed. These stoves work best if they are filled to capacity with coal. Spinner knobs or sliders on the ash pan door allow you to vary the amount of combustion air which controls the heat output. A low fire is possible with a full load of coal by limiting the combustion air.
The stoker style are mechanically filled from a bin or hopper by either an auger or pusher block delivery system (similar to a pellet stove). A stoker will have combustion air supplied via a fan through a grate or burn pot. As the coal burns into ash it either falls off the grates or is pushed out of the burn pot into the ash pan. The burn rate and be varied by adjusting the feed rate as well as the combustion airflow.
There are advantages & disadvantages of each and personal preference as well as logistical issues with the installation contribute to determining the best type for each individual. For example, stokers require electricity, hand fed stoves do not so if you have frequent power outages and no generator a hand fed may be the better choice. However, if for example you need to use a power vent because you don’t have a chimney, then a stoker style must be used. These are only a couple examples of the differences to be considered when deciding which type appliance is right for you.
There are multiple types of either hand fed or stoker. There are free standing stoves, fireplace inserts, hot air furnaces and hot water and steam boilers. The climate, heat load of the structure, what you want to get out of your system, space and your budget will guide you to the best long term choice.
If you require a lowest initial cost solution that will supplement your more traditional heat system, then a free standing or fireplace insert hand fed or stoker are the first solutions to review. While creating a lot of heat, it may be a challenge to circulate the heat these units create throughout the house. It depends on the layout and airflow of each house as to how well they work.
If you require a coal burning central heat source and the higher initial cost is not a deterrent, then the coal boiler or coal furnace are solutions to investigate. These units are centrally located and distribute the heat through ductwork or baseboard/radiators/in floor systems the same as a traditional oil / propane burner. These units can be zoned to deliver the heat as it is called for from different areas of the structure so the operation can be more efficient.
The coal itself comes in different sizes and the style appliance will require different sizes to be burned. Stokers usually burn the smaller size buck, rice or pea sized coal while hand fed usually burn the larger pea, nut or stove sized coal. Coal can be picked up or delivered, in 40lb or 50lb bags (palletized) or loose (bulk) by the ton. Depending where you are located coal can be bought from the coal breaker, a coal broker, a local dealer / delivery business or local hardware / feed store. The storage options available at your site will lead you to the best delivery system. For bulk delivery allowing a storage area of 40cubic feet per ton is recommended.
The hand fed stoves need a chimney for exhaust. Masonry chimneys with a tile liner will last indefinitely. A Class A stainless steel double wall insulated chimney can be used but these are known to deteriorate over time from corrosion. Beware of anyone trying to sell you on a SS liner for a masonry chimney. Instead of using a chimney, stoker stoves might use a power vent or direct vent for exhaust in which a fan pulls or pushes exhaust out the flue pipe. Unlike a wood stove, coal does not produce creosote so chimney fires are not a concern. Fly ash from coal will accumulate in horizontal sections of flue pipe so periodic cleaning will be necessary. You will need to determine the best safe interval for your installation by checking the flue pipe after burning a ton of coal observing the level of fly ash and scheduling cleaning based on coal usage, not time. The use of a manometer can be helpful for monitoring this.
Further information can be found in the forum areas that focus on the specific types of coal appliances. The search box function is also very useful. Enter a keyword that matches your interest (such as MPD or manometer or Glenwood) and press the ‘Search’ button and relevant threads will be listed that you can browse. If your questions have not been addressed by this introduction or by other threads, please start a thread and ask. There are a lot of years of coal burning experience waiting to be shared here.
Edit to add...this was a collaborative effort and an effort was made to not get too detailed here to keep it a manageable length....how successful that effort was is a matter of opinion!