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Furnaces that are capable of burning coal usually will burn both
Bituminous and Anthracite coal. Anthracite is perhaps the best
coal fuel because of its long even burn time, high heat output,
and cleanliness which make it a good choice for the home. How-
ever, keep in mind it is a much more diffi
cult fuel to use, requires
more care and patience, is not so widely available, and is usually
much more expensive than Bituminous.
SIZE OF COAL
Most sizes of Bituminous Coal will work in a coal furnace; for
best results we recommend large “nut” coal to small “egg” coal
(1-3/4” diameter to 4” diameter). When burning Anthracite, use
“egg” or “broken” with sizes between 2-5/16” thru 4-3/8”. Note
that it is important to the long life of your stove to buy coal which
has been sized and cleaned. Cleaning insures removal of rocks
and other minerals. Never use coal smaller than 1” or larger than
5” in diameter. Small sized coal will smother the fi re. Too large a
size of coal will not burn well.
STOVE OPERATION
All coal fi res should be started with wood which will allow the
fi re to get hot enough to ignite the coal. Th
e best ignition fi res
utilize dry pine or other resinous soft woods as kindling, with
hard wood (oak, hickory, ash) added to increase the heat prior to
addition of the coal.
Before starting the fi re, open the stove pipe damper (if equipped),
turn the thermostat to high, open the ash pit door and feed door,
place newspaper and fi nely split kindling on the grate, light the
paper, add larger hard wood aft er the kindling is burning bright-
ly. Caution: Never use gasoline, lantern fuel, kerosene, charcoal
lighter fl uid, or other fl ammable liquids to start or freshen up a
fi re in any heater. Place the larger pieces of wood on the fi re so
that they are slightly separated and form a level for the addition
of coal. It will take 10 to 20 minutes before this wood is thor-
oughly ignited. Adding coal too soon will cut the air supply and
smother the fi re.
BURNING BITUMINOUS
Once your kindling and wood fi re has produced a bed of well
established coals, start adding coal in layers allowing each to ig-
nite before adding more. Bituminous has a high volatile content
and, as a result, should be fi red with the “conical method” - with
the highest portion of your fi re bed in the center of the fi rebox.
Th
e fi rst fl ames will be long and generally orange or yellow and
produce quite a bit of smoke. As the gases burn off the fl ames
become shorter, change color and produce less smoke.
Once the fi re is WELL ESTABLISHED add coal to the center of
the fi rebox forming the cone. Burning in this fashion allows heat
to drive off the volatile gases, and turbulence created increases
the burn effi
ciency. Th
ere will have to be some experimenting
with the individual setup as no two chimney’s or installations are
going to be the same. Just remember to allow enough air to enter
the fi rebox and keep the stove pipe damper open so that volatiles
are properly burned. Before refueling, take the time to break up
the cone a little with a poker, especially if it has caked over or
formed a crust. But, be careful not to mix the coal as this increas-
es the chances of forming clinkers. When shaking the grate(s)
be gentle. Just a few short movements - a couple of “cranks” - is
better than a lot of agitation. Th
e objective is to remove a small
amount of the ashes without disturbing the fi re. Stop when you
see a glow in the ashes or the fi rst red coals fall into the ash pan.
Excessive shaking wastes fuel and can expose the grate(s) to very
high temperatures which can cause warpage or burnout.
For overnight operation (long duration burn time) shake the fi re
and add coal, retaining the center cone. Once the volatiles are
burned off , close the feed door and adjust the stove pipe damper,
if equipped. Th
en adjust the thermostat to the desired heat level.
More MAINTENANCE will be needed with bituminous coal
than with anthracite coal as more soot will collect on heating
surfaces and in pipes, requiring more frequent cleaning.
ANTHRACITE
Add a thin layer of coal (preferably smaller chunks) to the wood
fi re, being careful not to disturb it too much or cut off the draft .
Th
en, add a second heavier layer aft er the coal is ignited and
burning well. If necessary, add a third layer to bring the coal up
to the top of the front liner (not above!). Be sure to close the ash
door.
Before adding further fuel, be sure to leave a red spot of glowing
coals in the center of the fi rebox to insure that the fi re has not
been smothered and to help ignite the gases given off by the new
charge. A deep charge will give a more even heat and a longer
fi re, but it may take one to two hours before the whole bed is
fully ignited.
When the fi re is well established and the room is becoming
warm, partially close the dampers. Some experimenting will
have to take place with each particular setting of all dampers and
controls as the chimney provides the draft necessary to not only
exhaust the smoke, but to pull combustion air into the heater as
well - and no two chimney’s perform the same. Under ideal draft
conditions, one should be able to turn the secondary air supply
below the feed door (some models) to a near closed position -
but leave the ash pit damper at least partially open to prevent the
fi re from going out. Adjust the stove pipe damper to reduce the
draft on the fi re. With anthracite there will be short blue fl ames
above the coal, except when the fi re is started or a new charge is
added. If, however, there is no fl ame then the fi re needs more air
from the bottom (unless it is near the end of its burn cycle and
needs to be recharged).
Only when the coal is burned down to half its original depth it
is time to add fresh coal. When doing so, open the stove pipe
damper and turn the thermostat damper to high, which will al-
low the fi re to burn off any accumulated gases. Open the feed
door, and with a small rake, hoe, or hooked poker pull the glow-
ing coals to the front of the fi rebox. Try not to disturb the fi re too
much. Next, add a fresh charge to the back being careful not to
seal off the top. Close the feed door, but leave the spin damper
(or thermostat) open for a few minutes until the volatile gases
have burned off . It is not necessary to shake down the ashes each
time you refuel the furnace. Experience will be your best teacher.
BULLETIN RC454
A GUIDE TO BURNING COAL IN YOUR FURNACE
