David
E. Baker
University of Missouri Extension
With
ever-increasing fuel costs, heating with wood has again become
very popular with Missourians. But this increased use of wood-heating
equipment brings with it the need for constant, careful attention
to assure the safe and efficient use of this heat source.
One area often ignored is the special care needed for the
chimney. This guide provides general information on cleaning
chimneys.
Creosote
accumulation, which is described in "Wood Stove Maintenance
and Operation", is the main reason for cleaning a chimney.
If the buildup of creosote on the chimney's inside surface
ignites, a chimney fire results. Chimneys need cleaning to
prevent this buildup and thus reduce the possibility of a
chimney fire.
The
extremely high temperatures (up to 2,000 degrees F) of a chimney
fire can damage the chimney. The heat can warp metal chimneys
and crack the tile liner on masonry chimneys.
Never
use water on an extremely hot chimney fire, since this quick
cooling can also crack the tile liner or warp the metal chimney.
After the fire has been extinguished, have the chimney checked
for warped metal or a cracked tile liner.
If you
don't repair cracks or holes in the flue, the next chimney
fire could be even more dangerous. Even during normal use,
the sparks generated by the fire in the stove could go through
the cracks or holes into the attic or the framework surrounding
the chimney. This could cause a serious house fire, resulting
in loss of property and possibly loss of life.
To avoid
this tragedy, you need to establish a cleaning schedule that
will free your chimney of creosote buildup. This schedule
can range from once every couple of weeks to no less than
once a year. How often you clean the chimney depends on the
amount you use your stove, the type of wood you burn, the
type of wood- burning unit you have and the way you operate
the unit.
If,
however, a chimney fire occurs, follow these steps to reduce
your losses:
- Call
your local fire department immediately and give them your
name and address.
- If
there is a fire in the stove or fireplace box, extinguish
it with a multipurpose dry-chemical extinguisher. As some
of the chemical travels up the chimney, it may extinguish
the chimney fire.
You can
either clean the chimney yourself or hire a professional chimney
sweep. Chimney sweeps who will do a thorough and professional
job are available in many communities. Watching a sweep clean
your chimney would not only be educational, but would also
help you decide whether or not to tackle the job yourself
next time.
Before
deciding to clean your chimney yourself, consider your physical
condition. Cleaning a chimney can be strenuous work. Pulling
a chimney brush the height of the chimney can strain the back
and other muscles. Make sure you are up to the job before
starting.
If you
do decide to clean your chimney yourself, make these preparations
before beginning the actual cleaning job.
- Gather
the basic tools that you will need:
- Powerful
flashlight
- Drop
cloths
- Wide
masking or duct tape
- Ladder
- Mirror
(helpful for looking up the chimney from the bottom)
- Bucket
- Industrial-type
shop vacuum (Don't use a household vacuum cleaner because
the fine dust can ruin the motor's bearings; also, some
of the dust can go through the vacuum cleaner's filter
into the room.)
- Goggles
or a face shield
- Dust
mask
- Old
clothes and gloves
- Make
sure the chimney is structurally safe. If it is not, it
can fall apart when a horizontal load such as a ladder or
your weight leans against it.
- If
you are cleaning a fireplace chimney, take the damper plate
out; it is usually attached to its support by a couple of
cotter pins. Be careful - the metal can be brittle because
of exposure to extreme heat.
- Using
a powerful flashlight, check the openings from the top and
bottom for obstructions such as bird's nests. Also, check
the extent of creosote buildup. The largest concentration
of creosote should be in the upper one-third of the chimney.
- Seal
off the fireplace opening by taping a damp sheet over it;
otherwise you could end up with quite a mess in the house.
On a wood-burning stove, remove the stovepipe from the chimney
and cover the opening. On many chimneys, you will have an
outside bottom clean-out. Make sure you can open it before
you start cleaning.
Now you
are ready to start cleaning the chimney. The best time to clean
is when the chimney is still warm, since creosote comes off
a warm surface easier than a cooler surface. But make sure the
fire is completely out.
The
following are some of the more common methods for cleaning
chimneys:
Wire
chimney brush. The best method for cleaning your chimney
is scraping it with a wire chimney brush. The brush may seem
expensive, but for people who burn a lot of wood and must
clean their chimney more than once a year, a brush gives the
best results.
You
can buy brushes from most retail outlets that sell wood-
burning stoves or fireplace equipment. Brushes are available
in different sizes depending upon the shape and size of
your flue. Buy a brush designed to fit your flue.
Some
brushes have a rope attached to one end to pull the brush
up and down the chimney. For this type of brush, attach
a weight of some kind to the other end to pull the brush
down the chimney. Wrap cloth around the weight so it doesn't
damage the chimney if the weight bounces against the inside
surface.
Other
techniques. There are other techniques you can use with
some degree of success, such as scraping the chimney with
a burlap bag filled with straw or tire chains, chicken wire
rolled into a ball, etc. The main disadvantages of these
alternatives is that they are not able to provide enough
abrasion to clean all the creosote out of the flue.
System
management. Another cleaning technique that deserves
careful consideration is system management. You can eliminate
much of the creosote buildup with correct operation of the
system. Burning well-seasoned wood cuts down on creosote
buildup.
If
you own one of the new "high efficiency" stoves, you may
face special problems. These stoves increase heating efficiency
by allowing less heat to escape through the flue. This results
in lower metal temperatures in the flue. Since creosote
condenses more easily on cooler surfaces than on extremely
hot surfaces, this type of stove is particularly prone to
creosote buildup. To solve the problem, burn an intense
fire in your stove for at least one-half hour daily with
the damper open. This should burn off the accumulated creosote
in small quantities and reduce the potential for a chimney
fire.
Keep
in mind that you also need to clean smoke pipes used with
wood-burning furnaces and stoves. Remove the pipe carefully
and take it outside where it will be easier to clean. Tape
a bag or place a bucket at one end of the pipe to collect
the creosote for disposal. A long-handled wire brush will
normally clean most of the creosote buildup off the stovepipe.
Now that
the chimney is clean, it's time to go back inside the house
to clean up the soot and creosote that has fallen to the bottom
of the chimney. If you are cleaning a fireplace, carefully
remove the seal from the fireplace opening and sweep the soot
and creosote into containers. Make sure you sweep out the
accumulation on the smoke shelf above the damper, too. It
is better to use an industrial or shop vacuum cleaner for
this job. After this initial cleanup, use a wire brush to
scrape off the deposits from the inside of the fireplace and
from around the smoke shelf. Tidy up the area, and you're
finished.
Remember,
chimney fires are very dangerous and are a major cause of
wood-burning related house fires. The more you do to keep
your chimney in good working condition, the safer and more
efficient your wood-burning operation will be.
Disclaimer
and Reproduction Information: Information in NASD does not
represent NIOSH policy. Information included in NASD appears
by permission of the author and/or copyright holder. More
NASD Review: 04/2002
This
document is
GO1735
,
published by the University Extension, University of Missouri-Columbia,
Columbia, MO 65211. Publication date: October 1993.
David
E. Baker, University Extension, Department of Agricultural
Engineering, University of Missouri and Lincoln University,
Columbia, Missouri 65211.
Issued
in furtherance of Cooperative Extension Work Acts of May 8
and June 30, 1914, in cooperation with the United States Department
of Agriculture. Ronald J. Turner, Interim Director, Cooperative
Extension Service, University of Missouri and Lincoln University,
Columbia, Missouri 65211. An equal opportunity institution.
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