Home heating is now
the #1 cause of residential fires.
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Please take a few minutes
to review this material.
In less time than
that takes,
a stove or chimney
fire
could completely
change
your home
or your life.
|
Go To Chimney and
Stove Fires, Info (below)
Go To What To Do if a Chimney
or Stove Fire Happens (below)
WOODBURNING SEASON REMINDER:
Schedule an actual date on your calendar, before using your
stove(s) or fireplace in the fall, to clean your stovepipes or stacks.
Stovepipes and chimney flues should be inspected and cleaned each
season, before using your woodstove or fireplace.
Creosote
is a sticky, powdery, shiny, brittle
and hard-glazed substance, dark brown or black with an unpleasant
odor, resulting from the condensed wood gases and liquids
of unburned fuel.
It forms highly combustible deposits
that coat the inside walls of chimneys and woodstoves. The
more it accumulates, the greater its potential fuel will be
when it ignites.
Creosote build-up is a time bomb waiting
to happen, and can add significant fuel to a fire situation.
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How do you determine creosote build-up?
Check your stovepipe by tapping the pipe with a screwdriver: it will
"ping" if it is clean. If it "thumps," it needs
to be cleaned. The more creosote, the duller the thump, and the closer
you are to a stovepipe fire. If creosote is building up excessively,
signs include drips out of the joints, a dull sound if the connector
is tapped, and blockage of the chimney and loss of draft, evidenced
by smoking. Large accumulations should be removed mechanically, because
the excessive amount of fuel deposited in the chimney or flue could
be damaging even if the fire is carefully controlled.
Signs of wear and tear:
Check for cracked or warped metal liners, corrosion, rust, broken
or missing bricks, bent metal chimney pipes, thin spots and wear in
the firebox and stovepipe, creosote deposits, bird nests, and other
foreign material. Clean the stovepipe or flue thoroughly, and make
any necessary repairs. Be sure that any pipe sections you've taken
apart are re-secured, and wire screens or screened stovepipe caps
are replaced firmly. Any damaged pipes, fittings, loose mortar, worn
cement or cracking should be attended to.
When choosing a new stove:
Stoves built of cast iron or sturdy steel plate are preferred over
those made of lightweight, thin-gauged materials. A stove too large
for the intended area may not be able to burn hot for 15-30 minutes
each day, which will increase the probability of increased creosote
accumulation. Seasoning or breaking in a new stove should be done
with care and patience. Follow the manufacturer's or dealer's instructions.
Some stoves, especially those of cast iron, may require up to a total
of 24 hours of low-heat fires to condition the metal.
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Safe stove & fireplace installation:
Make sure your heating appliance is installed correctly. Oregon
State law requires a permit to be obtained for the installation
of any solid fuel-burning appliance. Obtaining a permit is in
the best interest of the homeowner, since the accompanying inspection
assures that the installation is done properly.
An illegal or improper installation could affect fire insurance
coverage and the ability to obtain financing when the property
is to be sold. There have been instances in which installations
done by contractors have not been done properly. Be certain
that your installer obtains a permit so that the completed work
is inspected and approved.
A metal tag on the appliance indicates whether it is listed.
A listed stove has been certified by an approved testing agency
and has complied with nationally recognized safety standards.
The stove must be installed according to the manufacturer's
instructions. Unlisted stoves must be installed in accordance
with local building codes. |
Placement & Location of Heating Appliances:
A stove or fireplace should sit on a non-combustible surface,
usually asbestos or firebrick, with adequate clearance on all
sides from anything that can ignite. The proper distance is
a minimum of 18 inches from combustible walls or other flammable
material.
Heat radiating from a stove to a combustible wall is a common
cause of house fires. Heat causes a "baking" effect
on wood inside the wall, which reduces the ignition temperature
at which a fire may easily start.
Suitable heat barriers can reduce required stove clearance
from the wall, and guard against overheating of the surrounding
area. Stove joints should be secured with at least three screws,
and installed so that upper sections fit into lower sections. |
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Cleaning:
Properly sized chimney brushes should be used
to clean a chimney flue: use two brushes, one
to fit the reduced size of the flue, caused by creosote deposits,
and a second one to fit the actual chimney.
An industrial vacuum cleaner may be needed
to control ashes and soot. (Furniture should be protected with
drop cloths). |
If you plan to use an airtight woodstove every
day, clean the stovepipe once a month.
Twice a year is the recommended minimum for all other stoves
and for chimneys.
Specialized tools are required to properly clean your
stovepipe and chimney.
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Hire it out?
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If your roof is precarious or you don't like
heights or getting sooty, hiring this job out might be preferable.
Professional cleaners have the experience and the tools: the
ladder, industrial-strength shop vacuum, brushes with extensions,
and dropcloths that you'll need - and they dispose of the soot
and creosote.
They should check pipe interiors, screens, fittings and joints,
as well as evaluate the overall condition of your burning unit,
and inform you of the results.
If you handle your own cleaning, care while on a ladder and
on a roof is advised. An additional person to hold the ladder
steady, hand tools so you don't have to lean down for them,
or just to help get things cleaned up later and to be sure you've
come down off the roof safely, is also advised. If you need
to borrow tools or a ladder, the Fire District may be able to
assist. Give us a call if you have any questions. |
How does creosote occur? When wood burns, the combustion
process is never absolutely complete. The smoke that results from
incomplete burning contains creosote. When the stovepipe and/or chimney
flue temperature drops below 250 degrees F., creosote will condense
on its interior surfaces. At very low temperatures (below 150 degrees
F.), the creosote deposits are quite fluid. If this condition is allowed
to continue, they can become very hard, glass-like in appearance,
and difficult to deal with when a cleaning is needed.
The amount of creosote that will condense out of the smoke depends
on several factors: the species and dryness of the wood, the density
of the smoke, and the temperature of the flue. The importance of burning
seasoned wood cannot be over-emphasized.
See our firewood page for
information on wood types and fuel ratings.
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Gaining maximum operating efficiency and limiting creosote:
The skillful stove operator tries to limit creosote build-up because
it has a corrosive effect on any metal within the heating system.
It also interferes with the draft of the chimney.
Whenever a load of wood is added to the stove, the draft controls
for combustion air should be opened for 10 to 30 minutes. The length
of time will vary according to the amount of fuel added to the stove
and the moisture content of the fuel. This procedure will drive off
some of the remaining moisture in the wood and allow it to burn evenly.
It will also raise the flue temperature and promote a stronger draft.
It is important to regulate the amount of heat from your stove by
the size of the fire that you build. This may require more frequent
re-fueling of the appliance, but the rewards will be more complete
combustion and increased efficiency.
It is better to burn a small fire with plenty of combustion air than
to build a large fire and let it smolder for lack of oxygen. Shutting
down the oxygen supply greatly, to decrease the stove temperature,
results in an air-starved fire. An air-starved fire produces more
creosote condensation because of increased smoke density and cooler
flue temperatures.
Newer, more airtight stoves create much
more creosote than older stoves and fireplaces, and can produce
enough creosote for a fire within just three days.
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An air-starved fire will also send large amounts of
particulate pollution into the air surrounding your home. It is wasteful,
too, because much of the volatile gas which would normally burn, were
it given enough oxygen, is simply exhausted up the chimney along with
its heat value.
Small fires with plenty of oxygen burn cleanest. Start out small
and add fuel gradually, staying within a safe operating range. Burn
briskly the first 30 minutes; maintain a moderate rate thereafter.
A good rule of thumb is to get the temperature up to a stovepipe thermometer
reading of 450 degrees F. for the first half-hour, and to keep it
at an average of 300 degrees thereafter, each day that you start your
stove.
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A magnetic stove thermometer
(as shown at left) attaches to the stove and enables you to
monitor surface temperatures. It helps you set air intakes for
appropriate combustion levels, thereby minimizing creosote accumulation.
It lets you know when it's time to reload, when to close the
damper, and warns of over-firing.
A catalytic thermometer probe looks like
a stove pipe thermometer, but is installed directly above the
combustor, and lets you know exactly when your combustor has
reached its point of maximum efficiency. A small hole must be
drilled in the cast iron to install this probe. |
A draft gauge mounts permanently on your stove pipe,
enabling you to measure your stove system's draft continuously and
accurately. The amount of draft can affect the operation of your stove
and can fluctuate with wind and temperature conditions.
Another key to limiting creosote
is to refrain from closing the damper tight at night, which
will starve the fire of the necessary oxygen for the combustion
process.
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Other tips for successful stove operations:
Efficient, slow-burning stoves may not keep your chimney or stovepipe
hot enough to burn out creosote, so build a roaring hot fire at least
once a week, but do NOT over-fire.
Over-Firing: A common mistake of novice wood burners
is accidental over-firing of their woodstove. Over-firing is visible
when your appliance metal begins to glow red. This happens when the
stove is left unattended and the fire has enough oxygen to eventually
run out of control. Over-heating can be the result, and the woodstove
is likely to pay a real penalty. Over-heating may cause steel stoves
to warp and cast iron stoves to develop cracks.
Backflashing: Although uncommon, backflashing or
"back-puffing" presents some hazards, and therefore demands
mention. It occurs when the combustion chamber of the stove fills
with unburned, volatile gases. If the stove door is suddenly opened,
oxygen rushes in, mixes with these gases, and a minor explosion occurs.
It happens most often when the woodstove has been in a very slow-burn
mode (air-starved fire) for a period of time, or when a fresh load
of wood is added on top of a hot bed of coals, and the combustion
air is limited. If the stove operator is leaning down to load wood
or check the fire, he/she may get caught in a flash of burning gases.
Prevention is easy: follow the procedure of opening the damper, opening
the draft controls for combustion air for a full half-minute. Then
open the door slowly.
Using manufactured logs or coal: Burning manufactured
"pressed logs" and coal should be done only when the stove
manufacturer has specifically approved of the practice. These types
of fuel often burn at unusually high temperatures, which may cause
damage to the appliance due to over-heating.
Trash Burning: Woodstoves are designed for burning
wood, not garbage or trash. Some types of plastic release very toxic
fumes when burned. Often the smoke and fumes from trash can be of
a poisonous and corrosive nature. Resist burning newspaper: it is
more valuable when recycled.
Fireplace tip: Don't close the damper when the fire
is still going, or when the embers are still hot: asphyxiation from
flue gases can result.
A clean spark-arrester screen over the chimney or around
the stovepipe cap provides good insurance against sparks,
which can ignite flammable material on and around the roof, or on
the ground around your home. The screen should be a wire mesh cloth
or expanded metal having approximately ½-inch (13 mm) squares.
(Ordinary, tighter mesh will quickly clog with soot, while larger
ones could allow passage of some sparks.)
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Stainless steel material is recommended, with
galvanized steel hardware cloth a poor second choice because
the coating soon burns off, making frequent replacement necessary.
Factory built chimney and stove manufacturers offer a variety
of chimney and stove cap options, with integral and accessory
spark arrester screens.
A metal or masonry hood over the chimney top will also reduce
wind and rain-caused backdraft and smoke problems. |
Non-combustible roofing and building
surface materials provide good insurance against fire
from sparks. (See our Community
Wildfire Protection Plan page for more recent information
about fire-safe building materials.)
The use of a protective screen (shown at right)
in front of your appliance also helps to protect your home.
Screens are relatively inexpensive, readily available, and easy
to use. |
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A common mistake is failure to securely close stove
or fireplace insert doors, allowing burning material to fall
back out and ignite the floor or other surrounding combustible
materials.
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Ashes and Ash Removal: Many
residential fires originate from combustible containers used
for ash removal. Even "day-old" ashes can contain
deep-lying hot embers.
Ashes should always be placed in a covered metal container,
and disposed of only after you are certain that all embers are
completely out.
Never place hot ashes in a container with other flammable debris,
which can then ignite, effectively becoming a burn barrel. The
radiant heat produced can then transfer to nearby fuels or structures. |
Back to Top
CHIMNEY AND STOVE FIRES:
86% of wood heat-related fires originate in the chimney
or stove pipe, when creosote ignites. If the stove
or chimney temperature is sufficiently high, it can ignite with
just one spark.
Creosote fire temperatures range from 1,200 to 2,000
degrees F.
The temperature and duration of the fire both depend upon the
accumulated thickness of creosote, the availability of oxygen,
type of heating appliance, type of chimney or stovepipe, and
other variant factors.
A stove fire heats the pipe and stove to a
cherry-red color. It will make a loud, roaring noise that breathes
like an accelerating locomotive. It may shake loose sections
of pipe if they are not secured together properly with sheet
metal screws. Flaming clinkers may be visibly emitted out of
the top of the stovepipe.
A chimney fire can quickly heat the chimney
to over 2,000 degrees (F), warping metal, cracking masonry,
bricks, tiles, and transfer excessive heat into adjacent walls,
ceilings, or other surfaces. |
Stovepipe and Chimney Damage:
Even if the house does not catch on fire, the chimney may need to
be replaced: flue fires can break down the mortar between bricks,
allowing flames and heat to come into contact with combustibles, and
decreasing the ignition temperature of supporting framework (carbonization).
If it is suspected that an extreme chimney fire has occurred, the
liner should be visually inspected. Slight buckling inward (¼
to ½ inch) is not cause for concern, but indicates that temperatures
may have reached the 2,000-degree F. level.
If serious damage of the chimney is seen, the affected chimney sections
should be replaced. In general, if the outer chimney is not discolored
and remains shiny, it is unlikely that any building structural damage
has occurred, since shiny surfaces are unlikely to radiate damaging
amounts of heat if the chimney is installed at the correct clearance.
When chimney and stove fires occur in stoves and heaters
that have air dampers and doors, reducing the air supply by closing
them is the best option. Then the combustion rate in the chimney or
stove stack depends upon its air supply.
Back to Top
IF A STOVEPIPE OR CHIMNEY FIRE
HAPPENS,
DO THE FOLLOWING:
1. Close the door and damper. Shut off the air supply
to the stove or fireplace. (It is optional to pour a cup of
hot water on the fire first.)
2. Call the Fire District.
3. Get everyone out of the house.
4. Hose down the roof. Avoid spraying
water down into the pipe or chimney.
5. Have the stovepipe or chimney
thoroughly cleaned and inspected before re-using.
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Other Protection: A home fire warning system
Many stove and chimney fires occur as the result of carelessness,
or neglecting the fire after loading fuel. This frequently occurs
when residents have turned in for the night, leaving the fire going.
You could have a flue fire while you sleep.
Fire produces toxic gases as well as smoke that actually numb the
senses. If you're asleep, or become disoriented by toxic gases, you
may not even realize that there is a fire. You can't rely on your
own senses to detect a fire.
By the time you know about it, it could be too late - unless you
have functioning, properly located smoke detectors
- the best early warning device there is.
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Every year about 5,000 people die
in home fires.
Most of the deaths occur at night in homes that
do not have smoke detectors,
while people sleep. |
It is estimated that 70% of home fire deaths could be avoided through
proper installation and maintenance of smoke detectors.
Clearly, while smoke detectors cannot provide complete fire protection
or prevent all tragedies, the universal use of these inexpensive safety
devices would save a lot of lives.
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You can do something about this now,
to prevent a disaster such as this:
Clean your flues and chimneys before creosote
has the chance to ignite,
and install and maintain working smoke detectors.
Back to Top
Smoke: What does it mean to your health?
Smoke from wildland fires often cause a number of people to be adversely
affected.
Some of these people, who are already vulnerable to breathing problems
caused by smoke because of previous asthma, heart or lung conditions
or because of age, become statistical cases in local emergency wards.
What exactly is smoke? The EPA (Environmental Protection Agency)
defines it as "particulate matter air pollution." This refers
to PM10 , a particulate matter less than 10 micrometers in diameter.
A particle this size is small enough to bypass our bodies' natural
defenses, and can cause both minor and severe health problems. (About
100 PM 10 's would fit in the period at the end of this sentence.)
Woodstove smoke, which results from unburned fuel, also contains
significant amounts of PM 10 pollution, from carbon monoxide (CO),
carbon dioxide (CO 2), hydrocarbons, water vapor, and many other organic
compounds.
While CO 2 and H 2 O vapor are harmless, CO and PM10 are respiratory
irritants, and are known to cause respiratory and cardiovascular illness,
as well as contributing to atmospheric visibility problems and property
damage.
Over time, both CO and PM 10 can be deadly. CO binds with the hemoglobin
in blood so that the blood cannot utilize oxygen. CO is 200 times
more likely to be bound to blood than oxygen. Because blood likes
to attach to CO more than oxygen, asphyxiation can occur in the presence
of oxygen.
PM 10 particles are small enough to bypass our bodies' natural defenses.
These particles lodge in lung tissue and can remain for up to a decade.
Chemicals stuck to the surface of these PM 10 particles can cause
cancer or other lung ailments.
The health consequences of wildfire smoke can be avoided by remaining
indoors.
Woodstove smoke emissions outdoors are not considered a problem,
due to our usual easterly wind flow patterns and good ventilation.
Such emissions are unregulated in the Colestin valley, which is outside
of Jackson County's air quality maintenance area.
But the effects of indoor smoke pollution upon those in close proximity
to a stove that doesn't burn cleanly are insidious.
Backdraft smoke, smoke while starting the stove, and breathing in
smoke particulates while re-loading or regulating a stove can contribute
to health problems over time. This smoke can be likened to second-hand
cigarette smoke, now known to be as potentially carcinogenic as directly
inhaling cigarette smoke.
If you use a woodstove for heat, you can limit the effect of indoor
particulates, as well as outdoor pollution, by burning dry wood in
a hot fire with plenty of oxygen. (See Stoves
and Flue Fires.)
Sources: "Burning Information for the Residents of Jackson County,"
published by the Jackson County Environmental Health & Air Quality
division of the Health and Human Services Dept., and "Buying
an EPA-Certified Woodstove," published by the U.S. EPA, Feb.
1990.
Further resources:
"Safer Flames - Homeowners would be wise to keep their chimneys,
stovepipes clean, or run the risk of a dangerous fire" - article
by Daniel Newberry, for The Mail Tribune, 31 October 2008. http://www.mailtribune.com/apps/pbcs.dll/article?AID=/20081031/LIFE/810310324
