Q: What is the best wood for a wood burning
stove ?
A: On a pound-for-pound basis all wood contains just
about the same amount of energy. However, on a volume basis
there is a great difference in the heat given off by different
woods. As a general rule, so-called "hardwoods" are more
dense than "softwoods". They burn longer and give off more
heat than softwoods. The following table should help you
in choosing which woods to burn:
Species Having High Heat Value
(1 cord = 21,000,000 - 24,000,000 BTU = 200-250 gal. of fuel
oil or 250-300 cu. ft. of natural gas)
American Beech
Apple
Hickory
Ironwood
Red Oak
Sugar Maple
White Oak
Yellow Birch
Species Having Medium Heat Value
(1 cord = 17,000,000 - 20,000,000 BTU = 150-200 gal.
of fuel oil or 200-250 cu. ft. of natural gas)
Big Leaf Maple
Eastern Larch
Elm
Red Maple
White Ash
White Birch
Species Having Low Heat Value;
(1 cord = 12,000,000-17,000,000 BTU = 100-150 gal. of
fuel oil or 200-250 cu. ft. of natural gas)
Aspen
Cottonwood
Hemlock
Red Alder
Redwood
Sitka Spruce
Western Red Cedar
White Pine
Q: Where do I get firewood?
A: For many people the most satisfying way is to
cut your own. Even if you do not own a woodlot, you may find
that someone who does would be happy to have you improve
his woodland by culling out poor quality hardwoods. In many
states you are allowed to cut in state forests. You can find
out by contacting your county forester or your state's department
in charge of parks and forests.
As pointed out elsewhere in this presentation, even if you
have to buy firewood, you can invariably save money over
buying other kinds of fuel. You can usually find firewood
vendors listed in the Yellow Pages or in the classified pages
of your local newspaper.
Look for someone who is honest about the types of wood he
offers and how well seasoned it is. There is nothing wrong
with buying green, unseasoned wood as long as the price reflects
the fact that you cannot use it until you have taken the
time to stack it and dry it. (More about that, below). It
is important to understand the unit of measure most commonly
used for wood: the cord.
Q: How much wood is in a cord?
A: A standard cord measures 8 feet long, 4 feet high
and 4 feet wide or 128 cubic feet. Depending on the size
of the pieces of wood and the care with which it is stacked,
the actual amount of wood in a cord will vary considerably.
It is legitimate for a cord to be as much as 1/3 air. However,
no matter what length of firewood you buy, it must stack
up to 8' x 4' x 4' to be a cord.
Note: If you buy a cord of 4 foot lengths of wood and
cut it up yourself, the resulting pile will take up less
than a cord because of all the sawdust you create. A cord
put into 16-inch or 24-inch lengths will shrink by 14 percent,
or 18 cubic feet, in volume.
Another measure by which wood is sold is the run. A run
is 1/3 of a cord and measures 8 feet by 4 feet by 16 inches.
Q: So, what is a "face cord"?
A: Wood is often advertised as so much per "face
cord". But you should be very careful about buying wood on
this basis. A "face cord" is a non-standard measurement that
should never be confused with a cord. It measures 8 feet
long by 4 feet high, but is only as deep as one length of
wood. Obviously, it is possible for a face cord to contain
considerably less than one cord of wood. Before buying a
face cord of wood, you ought to use your calculator to figure
how much you are paying on a cord basis; you may be unpleasantly
surprised.
Q: Everyone says you should let your wood dry for a year
before using it. Is it really necessary to burn seasoned
wood?
A: The simple answer is yes. Seasoned wood will burn
better, provide more heat, and cause fewer problems than
green wood. When first cut, wood is often more than 50% water
by weight. It takes a lot of energy to drive off this water
-- which is what has to happen before the wood can burn.
So green wood is hard to light, doesn't produce much heat,
and smokes a lot. The water in green wood can also cool the
catalytic combustor to the point that it will no longer function
and/or cause smoke to condense on the inside of your chimney's
walls as creosote.
What is important is the dryness of the wood (optimally
15-25% water content), not the period of time it has been
drying. At one extreme, some professional firewood suppliers
use wood kilns to dry wood in only a few days. At the other
extreme, unsplit, improperly stacked wood will rot long before
it is ever dry enough to use.
Q: So, how do I tell if my wood is dry enough to use?
A: Partly, being able to tell if wood is dry is a
matter of experience. However, some of the signs you can
use to tell if your wood is dry are:
1. The wood is lighter than green wood. However,
be aware that the density and weight of wood also depends
on the species. White oak is denser and heavier than white
pine. Still, dry white oak is lighter than wet white oak.
2. The bark is loose. As wood dries it tends to
lose its bark. This is not an absolute rule, but when your
wood is dry you should notice a good bit of barkless wood
and free pieces of bark.
3. The color of the wood fades. Different types
of wood are more or less colorful, but for all species,
dry wood is more subdued and faded looking than green wood.
4. The wood shows radial cracks. As wood dries
it shrinks. As a result, it usually develops cracks, visible
at the ends, which radiate out from the heartwood to the
bark. Since the wood will often start to crack before it
is completely dry, the presence of radial cracks is not
a fool-proof sign that the wood is ready to burn. But,
the total absence of such cracks is a good sign that it
is not ready yet.
5. The wood loses its sappy smell. Dry wood is
much less aromatic than green wood.
6. Dry wood makes a "crack" when hit. If you hit
two pieces of seasoned wood together, they will make a
resonant sound, like a bat hitting a baseball. Green wood
makes more of a "thud".
Q: I have green wood, what do I do now?
A: If you have the time, carefully stack your wood
and let it dry. If you have no other options, try splitting
the wood into smaller pieces, mixing dry wood or kindling
with it, and letting more air into the stove, so it burns
a little hotter.
Q: What is the best way to dry my wood?
A: The best way to dry your wood is to split it and
then stack it so that it is well-ventilated, covered and
off the ground. Storing wood this way for 4-6 months can
make a big difference in the efficiency of your stove.
Split wood has much more surface area than unsplit wood.
It also has surfaces that are not covered with bark. Therefore,
it will dry faster than unsplit wood. The ultimate example
of this is birch wood. Because birch bark is waterproof (which
is why Indians made canoes out of it), unsplit birch wood
will often rot from the inside without ever drying.
Wood not only takes up less space when stacked, but it allows
air to circulate around the wood. Good ventilation is the
most important factor in having dry wood. It helps to dry
the wood by speeding up evaporation. If you have the space,
you might want to employ a trick used by old timers. They
stacked their wood in long thin rows spaced apart, and at
right angles to the prevailing winds to ensure good ventilation.
Covering the wood and keeping it off the ground are important
because these practices keep the wood away from moisture.
Wood acts very much like a sponge. If it is exposed to rain,
snow or moisture in the ground, it will soak this water right
up, putting to naught all your efforts to dry it out.
With these basics in mind, there are a few simple rules
you will want to follow:
1. Do cover the wood, but do not drape a plastic sheet
or tarp over your wood pile so that it covers the sides
of the pile. This will trap the moisture in the pile and
the wood will not dry. If you can, make a simple wood frame
to raise the plastic cover a few feet above the wood. The
ultimate drying place is an open sided shed.
2. Use 2 x 4's, poles, or pallets or some other method
to keep your wood off the ground.
3. If you dry your wood inside, allow for adequate ventilation.
Wood stored in a heated space does dry faster. However,
drying wood gives off a lot of water. If you do not allow
for that water to exit to the outside you will probably
raise a bumper-crop of mold and/or mushrooms. Another reason
to be careful about storing wood inside is the fact that
ants, beetles or other unwanted guests sometimes ride along
on unseasoned wood.
Q: How do I go about lighting the wood burning stove?
A: For your wood burning stove to work you must have
a good draft from your chimney. It is, therefore, important
to check the draft before you light your wood stove. If the
draft is static, or if you have a downdraft, you will need
to correct this situation before you light the wood burning
stove. Otherwise, you might get some smoke back in the house.
To check the draft, open the side door and catalytic bypass
damper on the wood stove. Light a match in front of the flue
outlet of your wood burning stove. If the flame is pulled
into the flue outlet, you have adequate draft to light your
stove. If the flame doesn't move, or if it comes back toward
you, you do not have enough draft to light the stove, and
you need to correct this situation before kindling a fire.
To establish proper draft before lighting the wood burning
stove with the loading door and catalytic bypass open:
1. Open a door or window in the room in which the stove
is installed;
2. Wait a minute of two, and then try lighting a match
in the flue outlet again.
3. If the chimney draws, then light a small sheet of newspaper
in the flue outlet. This will get some heat in the chimney
and help to establish a good draft.
Opening a door or window for a few minutes in the room where
the wood burning stove is installed should reverse house
pressure and allow the chimney to begin to draw. This should
be evident the second time you light a match in the flue
outlet -- the flame should be pulled into the flue opening.
As an added measure you can warm the chimney and encourage
more draft by crumpling up a piece of newspaper into the
shape of a torch, lighting it and holding it at the flue
outlet.
If these measures have not been sufficient to provide a
good draft, you should review the information on wood burning
stove installation and proper ventilation located elsewhere
in our web page.
Having established that you have an adequate draft, proceed
to build your fire. Start with several sheets of newspaper
loosely crumpled. Make a mound of these in the firebox. Around
and on top of the paper, place, tentlike, small scraps of
dry wood. Dry softwoods like pine or spruce are ideal whether
they are construction scraps or dead branches from trees
in your yard. Touch a match to the paper. Once the kindling
wood has started to burn, add three or four small pieces
of firewood. Once they are burning briskly, you can gradually
build up the fire to the desired size.
After about 20 minutes, your fire should be burning hot
and with only a little smoke. Check the thermometer that
comes with your stove and see if the temperature indicates
that it is OK to close the bypass damper to engage the catalytic
combustor.
Q: Just what is a catalytic combustor?
A: The catalytic combustor in your wood burning stove
is a ceramic honeycomb device placed between the fire and
the stove pipe. The smoke from the fire passes through the
combustor before exiting the stove. The surface of the combustor
is coated with a thin layer of platinum or palladium. This
metal "burns" the wood smoke, reducing the stove's emissions
and helping to heat your house. To understand how this happens,
it is necessary to know something about fires and what happens
when wood burns.
Fire is a chemical reaction. For a fire you need three things:
fuel, oxygen and heat. The fuel and oxygen must be present
in the right proportion and the temperature must be high
enough. If these conditions are not met the fire will not
burn properly.
When a log is placed in the fire it undergoes a three stage
process:
First, all the water in the wood is driven off as
steam. (Doing this absorbs heat, lowering the fire's temperature
and reducing the amount of energy available to heat your
house. That is why it is so important to use dry, seasoned
wood in your stove. Even dry wood will contain some moisture,
but a minimal amount that will evaporate quickly.)
Second, the wood undergoes a process called "pyrolysis",
releasing gases which are burned or which escape as smoke.
(The burning of these gases causes the beautiful flames you
see in your stove.)
Third, the carbon in the wood burns as "coals".
High temperatures (in excess of 1100-1200 degrees Fahrenheit)
are needed for the gases to burn. Unfortunately, most wood
burning stoves cannot consistently produce temperatures in
this range and many of the gases never get hot enough to
burn. The result is woodsmoke that contains carbon monoxide,
soot, free hydrogen, tars, and other organic compounds.
The catalytic combustor causes the gases to burn at much
lower temperatures (around 500 degrees Fahrenheit) than they
would otherwise. The result is that your wood burning stove
emits only steam (carbon dioxide and water), and your chimney
stays much cleaner. Your stove also becomes much more efficient
because you are making use of the energy in the woodsmoke.
As noted above, using a catalytic combustor can increase
the stove's efficiency by up to 25%.
Q: How do I operate the catalytic combustor?
A: Operation of the catalytic combustor is relatively
simple. After about 20 minutes, the wood burning stove should
reach operating temperatures as indicated by the thermometer
supplied with the stove. Once it has done so, the catalytic
bypass damper is closed so that the smoke is drawn through
the catalyst. The combustor will ignite and begin to function,
burning the smoke and cleaning up the stove's emissions.
At this point, follow the Goldilocks rule. Like Goldilocks
with the three bear's porridge, the combustor is happiest
when it is neither too hot nor too cold. The combustor needs
to remain hot enough to function and not so hot that it is
damaged. Use of the stove thermometer will help you to operate
the stove in the correct temperature range.
Q: What maintenance does the combustor need?
A: You should inspect the "upstream side" of your
catalytic combustor periodically, and remove any fly ash
that has accumulated on it. (The "upstream side" of the combustor
is the side closest to the fire, and the side that the smoke
enters.) We recommend that you inspect and/or clean the upstream
side of the catalytic combustor after every 60 days of use
(more often if you suspect that the wood you are using is
not dry).
The upstream side can become partially obstructed with air-born
fly ash. If this happens, the catalyst's performance will
be impaired and the draft will be reduced. See the instructions
which came with your stove for how to clean the combustor
in your particular model.
If you are using your stove as a primary source of heat,
and burning it all day, every day throughout the cold winter
months, then your combustor should be replaced every 4-5
years. A new combustor will give you more heat for the wood
that you burn; it will help you to conserve wood, and your
wood burning stove will burn more cleanly.
Q: How do I tell if my combustor needs replacing?
A: There are three basic ways to tell if your catalytic
combustor is not working:
1. The smoke coming out of your chimney will be noticeably
darker;
2. The wood burning stove will not generate as high temperatures
as it once did; and
3. You may get a build-up of creosote or soot in the chimney.
Q: What about cleaning the wood burning stove?
A: You will, of course, need to remove ashes from
your stove. The most important thing about ash removal is
that ashes be placed in a metal container with a tight fitting
lid. The closed container of ashes should be placed on a
noncombustible floor or on the ground, well away from all
combustible materials, pending final disposal. If the ashes
are disposed of by burial in soil, or otherwise locally dispersed,
they should be retained in the closed container until all
cinders have thoroughly cooled. Live cinders can take up
to 36 hours to cool.
Never leave the ash container on a wood porch or deck or
on wooden steps. Never shovel ashes into a combustible container
like a cardboard box or a plastic pail. Do not use a vacuum
cleaner to remove ashes.
For specific directions on how to remove the ashes from
your model stove, follow the instructions that came with
it.
Q: How do I clean the window in my wood burning stove?
A: The window in the stove is designed to remain
clean during use. However, the window may soot up the first
time you use the stove. Don't be alarmed. As soon as the
stove temperature is high enough, the glass will clean itself
(i.e. the deposits will burn off) and it will stay clean.
Accumulations of this sort can also happen in the spring
and fall when temperatures are mild and wood is likely to
be damp.
To clean the inside of the glass, use finest (#0000) steel
wool. The glass is actually cast ceramic so the fine steel
wool won't etch or scratch it. (Warning: Be sure the fire
is out and the glass is cool before attempting to clean it.)
If you use a chemical cleaner, be sure that the inside of
the glass is dry before you start the next fire, so that
smoke or soot does not get trapped in moisture on the glass.
Q: What other maintenance needs to be done?
A: If the soapstone surface of the stove becomes
scratched or blemished you can use extra fine (#000) steel
wool to touch it up. Using the steel wool, rub the soapstone
with circular motion. This is the same type of steel wool
used by furniture makers to polish fine furniture and it
will not mar the surface of the soapstone.
If you need to remove deep scratches or gouges, use a more
abrasive material like 120 grit sandpaper or a coarser grade
of steel wool. After the scratch or gouge has been removed,
polish the area you worked on with extra fine (#000) steel
wool to restore its original finish.
If you need to refinish the cast iron parts with touch-up
paint, mask off the soapstone in the area that you wish to
paint by sliding pieces of paper under the edges of the castings.
(You will be able to push the paper under the soft fiberglass
rope gasket which is used to seal the seams.) Then, carefully
touch-up the exposed casting with spray paint. |
