Straight Answers to Burning Questions:
Quick Tips For Cleaner, More Efficient Wood Heat
Many benefits result from the decision to heat with wood:
Wood heat contributes to the conservation of the world’s non-renewable
Wood heat enhances the nation’s energy independence.
Heating with wood will save you money.
However, linked to these benefits is the environmental responsibility to
burn as clean and efficiently as possible. This guide will address
information on proper wood burning and provide tips to help you burn
smart and with low emissions to help protect your local environment.
RESPONSIBLE WOOD BURNING
Heating with wood is an American tradition. Yet, wood burning in the past
decade has bore little resemblance to wood burning done in the 1970s --
or even the mid-1980s. Today, important technological advances have
resulted in a new breed of clean burning, high efficiency wood stoves,
fireplace inserts and fireplaces, as well as cleaner burning fuels, such as
wood pellets and manufactured firelogs. However, with this new technology
comes the responsibility of proper wood burning techniques.
When heating with wood, there are four critical elements to help achieve
optimal economy, environmental responsibility and efficiency form a wood
stove or wood burning fireplace insert:
(1) The Wood Stove or Fireplace Insert
(2) The Installation
(3) The Operator
(4) The Fuel
THE WOOD STOVE OR FIREPLACE INSERT
Q. “How can I tell if a wood stove is a new clean burning, high efficiency
A. Regulations enacted by the U.S. Environmental Protection Agency
(EPA) require all wood stoves and fireplace inserts manufactured and sold
after July 1, 1992 to pass stringent emission tests. An EPA label identifies
a stove as a new clean burning, high efficiency model, and is found on
every certified stove or insert.
Q. “How can I tell if a stove or insert is sized right for my home?”
A. Consider your geographic location and climate, the number of rooms
you wish to heat, and construction features of your home such as room
size, ceiling height, and insulation. Ask a Hearth Specialty Retailer for
information on the best stove for your space heating requirements. To
locate a Hearth Specialty Retailer go to www.woodstovechangeout.org.
Q. “I already have an older stove. Is there anything I can do to make it
A. Yes. Even if you can’t upgrade to a new EPA-certified stove or
fireplace insert right away, you can still improve the performance of your
current stove. Have your wood heating system inspected by a certified
Hearth Specialty Retailer or by CSIA Certified Chimney Sweep to ensure it
has been properly installed. To locate a HEARTH Certified Specialist go to
www.hearthed.com or to locate a certified sweep, go to www.csia.org.
Ask the professional if your stove can be retrofitted with a catalytic
combustor. While this improvement won’t make your stove EPA-certified it
has the potential to increase the efficiency of your appliance. You can also
reduce emissions by burning only well-seasoned firewood or by starting
your fire with a firelighter product.
Q. “When installing a wood stove, what’s the first thing I should consider?”
A. That the wood stove and chimney work as a system. It is important for
the stove’s chimney system be sized properly, according to manufacturer’s
instructions. Whether venting into a masonry or metal system, make sure
the diameter of the chimney matches closely, but never smaller than, the
size of the stove’s flue outlet. Doing anything else adversely impacts
emissions and safety.
Q “Can I install my own stove, or should I have the installation done
A. The Hearth Products Association recommends that all stove and
fireplace inserts be installed by a specialist certified by the HEARTH
Education Foundation. This technician will be familiar with your model and
will have installed many others like it. This experience can save you time,
money and frustration in the long run. Plus, it gives you the confidence
your stove is installed properly and safely. For owners who choose to
install their own wood stoves, follow the manufacturer’s instructions
explicitly. NEVER proceed without professional advice if you have a
question. To locate a HEARTH certified specialist, go to www.hearthed.
Q. “Where can I find a qualified installer?”
A. A Hearth Specialty Retailer can provide you with professional
installation assistance. Ask the retailer about the installer’s credentials.
Does the installer have experience with the make and model of the stove
you are buying? Is the installer certified by the HEARTH Education
Q. “What is HEARTH?”
A. HEARTH is a nonprofit foundation formed to promote the safe and
efficient installation, maintenance and operation of solid fuel appliance
systems. The foundation offers educational programs designed to
upgrade the skills of professional installers and fire code inspectors.
HEARTH certification credentials are awarded to professionals who pass a
comprehensive examination. Credential must be renewed every three
years to remain valid. To locate a HEARTH certified specialist, go to www.
Q. “How can I tell if I am operating my wood stove properly?”
A. Check the exhaust coming out of your wood stove chimney; the smoke
is your operational barometer. If your fire is burning properly, you should
only see the white transparent steam of evaporating water, darker and
opaque smoke will only be slightly visible. The darker the color of the
exhaust, the less efficiently you are operating the appliance. It may be
necessary to adjust the operation of your wood stove to decrease the
opacity of the exhaust (that is, the density of the smoke). A 15% opacity
level indicates efficient operations, while a 90% level reflects unacceptable
polluting conditions; some state regulate opacity levels from wood stove
Q. “Why is wood smoke undesirable?”
A. Smoke, in the form of solid particles (“particulates”) and volatile gases,
is unburned fuel. An improperly operated wood stove fails to achieve the
high combustion temperatures necessary to burn the particulates and
ignite the gases. These gases and particulates contain half the heating
potential of your firewood. The loss of this fuel up the chimney amounts to
a loss of efficiency. Improperly operated wood stoves can also adversely
affect air quality. However, the use of EPA-certified wood stoves and wood
burning fireplace inserts, combined with the proper operation of all wood
burning stoves and inserts, can decrease the level of polluting emissions
by up to 85 percent.
Q. “Are there times when my wood stove or fireplace insert will emit more
A. There are two periods in the operation of a wood stove most vulnerable
to creating smoky emissions -- during startup and during refueling.
However, these smoky periods can be dramatically minimized by proper
Q. “What can I do to minimize the amount of smoke at startup and
A. Create the drafting conditions necessary to maintain clean combustion.
“Good drafting condition” occurs when your chimney consistently draws air
into the wood stove at a high enough rate to prove adequate oxygen for
complete burning. To create this draft, you must “preheat the chimney.”
Some chimneys require longer preheating periods than others, depending
upon their height, outside exposure and construction. Typically,
preheating requires 5-15 minutes of vigorous firing.
Q. “How do I preheat my chimney?”
A. At startup, remove all but a thin layer of ashes from your firebox. Insert
five or six crumpled individual pieces of newspaper and dry finely split
kindling or a firelighter. Firmly open the air supply (dampers) to the
woodstove and ignite the paper on all aides. You may find it necessary to
leave the stove door slightly ajar during the first few moments of the fire.
After the first load ignites, add more kindling until the chimney is
preheated. The fire should burn briskly and full of flame during the startup
if you are operating the wood stove properly.
When reloading, place finely split pieces of wood on the charcoal bed and
fully open the air supply. Using smaller pieces of wood during reloading
encouraged rapid reheating of the chimney.
You’ll know the chimney is preheated when each large piece of wood you
add to the fire burns vigorously, without a loss in intensity of the fire. Keep
listening to the sound of the air entering the stove. A constant and rising
movement of air signals that good drafting conditions have been achieved.
Some wood stove manufacturers provide specific guidelines for startup and
preheating phases involving the indirect monitoring of chimney exhaust
temperatures. Typically, chimney connector temperatures must reach 500-
600 degrees F. before the chimney is fully primed. Follow your
manufacturer’s instructions when temperature and startup procedures are
Q. “Once I have preheated my chimney, how should I operate the stove?”
A. Although all wood stoves require preheating during startup and
reloading, their operation afterwards vary somewhat. Wood stoves using
catalytic combustors require the monitoring of temperatures and air supply
to ensure the catalyst engages at appropriate times in the combustion
cycle. Generally, catalytic stoves require lower combustion temperatures
in the firebox to burn cleanly. At 500-1000 degrees F., the catalyst ignites,
burning the volatile gases and particulates. Non-catalytic stoves attain
much higher temperatures in the combustion path before the gases and
particulates burn. Always refer to your wood stove manufacturer’s
operation manual and follow the instructions for your particular make and
Q. “Do I operate my stove differently in cold vs. warm weather conditions?”
A. Yes. During the warmer seasons of spring and fall, control the total
heat output by limiting the amount of fuel (wood) rather than by closing
down the air supply. Make shorter, hot fires using more finely split wood.
The actual air supply setting will vary according to your stove instruction,
but the fuel loading will be consistently smaller. Let the fire burn out rather
than smolder at low air supply setting. When your home requires more
heat, restart the fire with kindling as always, but add smaller fuel loads.
This allows your stove to operate at maximum efficiency and with minimum
emissions. Avoid the temptation of building a big fire and then starving it
Q. “Is it important to have my stove and chimney cleaned?”
A. Yes. Smoke rising through your chimney may condense and build up
on the cooler inside walls forming a substance known as creosote. The
volatile substance can ignite and burn in the chimney. Many chimneys and
installations are unable to withstand these dangerous creosote fires; the
results can be tragic. Chimneys and vents for wood stoves and inserts
also perform the necessary function of directly venting the hot gases from
a fire away from the house. If the chimneys or vents are obstructed by
debris or animals the hot gases can be forced back into the home. At the
same time, wood stoves and inserts require service to ensure they are
Q. “How often should I have my chimney inspected and cleaned?”
A. The Chimney Safety Institute of America recommends that all chimneys
and vents be inspected on an annual basis and cleaned as necessary.
However, frequent stove or insert use may require monthly chimney
inspection and cleanings. Wood stove or wood burning fireplace
connectors (stove pipes) should be checked as often as every 2-4 weeks.
A CSIA Certified Chimney Sweep can show you the proper methods for
these more frequent inspections and can provide valuable insight into the
proper working of your chimney and/or vents. For more information about
chimney safety, go to www.csia.org or call 1-800-536-0118.
Q. “How often should I have my wood stove or fireplace inserts serviced?”
A. The HEARTH Education Foundation manuals recommend at least
annual inspection/service/maintenance for solid fuel appliances and
venting systems. The basis for that recommendation for solid fuel
appliances is the National Fire Protection Association standard NFPA
Q. “How can I make my fireplace produce less emissions so that I can still
enjoy a wood fire”?
A. You can install an EPA-certified wood burning insert or you can burn a
manufactured firelogs which produces more than two-thirds emissions than
firewood burned in an open hearth fireplace.
Q. “Does it matter what kind of wood I use?”
A. Your fuel supply should consist of a mixture of hardwoods, like maple or
oak, and softwoods, such as fir and pine. When first starting your fire, use
softwoods. They ignite easily and burn rapidly with a hot flame.
Hardwoods provide a longer lasting fire and are best used after preheating
the chimney. If hardwoods are unavailable, you can control your fire’s burn
rate by using larger pieces of wood.
Q. “Is it important to season wood before burning it?”
A. The seasoning, or drying, process allows most of the natural moisture
found in wood to evaporate, making it easier to burn. A properly seasoned
log will have 20%-30% moisture content. Wood only dries from the surface
inward so un-split pieces dry very slowly. To properly season wood, split
the logs as soon as possible and stack them in a dry spot for 6-18 months.
Pile the wood loosely, allowing air to circulate through the split logs.
Hardwoods take longer to dry than softwoods. Humidity and temperature
levels also impact drying time.
Q. “What’s the best way to load wood into my stove or insert?”
A. Avoid placing pieces of wood in parallel directions, where they may
stack too closely. Vary the position of the wood in the firebox to maximize
the exposed surface area of each piece of wood. Only use wood properly
sized for your stove’s fire chamber. Complete wood combustion requires
wood (fuel), temperature (heat), and oxygen (air) to burn completely and
Q. “Is there anything I shouldn’t burn?”
A. Never burn garbage, plastic, foil, or any kind of chemically treated or
painted wood. They all produce noxious fumes; these are dangerous and
highly polluting. Additionally, if you have a catalytic stove, the residue from
burning plastics may clog the catalytic combustor.
WOOD BURNING: CLEAN, EFFICIENT, RESPONSIBLE HEAT
Select an EPA-certified wood stove or inserts which produce up to 85
percent less emissions than those manufactured before July 1, 1992.
If you cannot install a newer stove or insert, enhance the capabilities of
your current appliance by following the tips above.
Make sure the stove’s installation and flue system are safe and appropriate
by having an annual chimney inspection and through periodic maintenance
on your stove or insert.
Remember how you burn determines the economy, environmental
responsibility and efficiency of your wood burning stove or insert.
Use dry, seasoned and split wood.
Never burn garbage in a wood stove.