Bricks that fall from the top and lodge at offsets or contracted sections
can sometimes be reached and dislodged by a long pole or sections of
pipe screwed together. They can be caught on a shingle or piece of sheet
metal shoved into a stovepipe hole or removed through a clean-out door. A
weighted cement sack filled with straw and attached to the end of a rope
may be pulled up and down the flue to remove soot and loose material if
the offset is not too great.
Trouble with creosote and soot can be reduced when one understands how
they are formed. Smoke and soot are caused by imperfect combustion,
usually due to one or all of the following conditions: (1) Lack of
sufficient air to the fire; (2) improper mixture of air with furnace
gases; (3) low furnace temperature; (4) too small combustion space so
that the gases reach the comparatively cool furnace surface before they
are completely burned and, as a result, soot or tarry matter condenses
and then passes up the chimney in the form of smoke. Soft coal causes
more soot trouble than hard coal.
If soot accumulates fast or trouble is experienced with unusual smoke
when firing, it is probable that the heating equipment is not being
operated properly. The manufacturer or installer usually is able to
suggest proper adjustments.
Investigations by the United States Bureau of Mines[5] have shown that
various materials on being burned or volatilized form a vapor or smoke
which settles upon soot; causing it to ignite at a lower temperature and
burn more easily. For soot to burn, the gases in contact with it must
have a temperature high enough to ignite it and sufficient air to support
the combustion. The effectiveness of burning varies with the composition
of the remover, but it also depends upon conditions being favorable. It
will usually reduce somewhat the soot in a furnace and smoke pipe but not
in a chimney. It has no effect on the ash mixed with the soot. This ash
not only does not burn, but prevents complete burning of the soot mixed
with it.
[5] Nichols, P., and Staples, C. W. REMOVAL OR SOOT FROM FURNACES AND
FLUES BY THE USE OF SALTS OR COMPOUNDS. U. S. Bur. Mines Bul. 360, 76
pp., illus. 1932.
Soot removers cause soot to burn and are fire hazards. The correct and
most thorough method of cleaning a chimney is to do so manually or to
employ modern exhaust or vacuum methods used by furnace repairmen.
However, it is inconvenient to remove soot and ash accumulations
thoroughly more than once a year; hence a remover may help to keep
the passages of stoves and heaters clear between annual cleanings, if
deposits of soot accumulate quickly and reduce the draft.
Likelihood of success in cleaning is greater when the deposits of soot
are thick, provided they do not cut down the draft too much. If burning
is employed, there is less risk when it is done frequently enough to
prevent large accumulations, which cause intense fires. Also, freeing
the heater and pipe of soot permits better fuel burning and higher
temperatures in the chimney flue, thus reducing the amount of soot likely
to be deposited on the flue walls.
Common salt (rock or ice-cream salt) is not the most effective remover,
yet it is the most widely used because of its cheapness, ease of
handling, and general availability. Use two or three teacupfuls per
application. Metallic zinc in the form of dust or small granules is
often used; however, a mixture of salt and 10 percent zinc dust is more
effective than either salt or zinc alone.
One of the most effective mixtures of materials readily available
is 1 part dry red lead and 5 parts common salt, measured by weight.
Shake these together in a can with a tight-fitting lid. As lead is
poisonous, wash the hands after using. One or two teacupfuls are used per
application.
Old dry-cell batteries contain suitable ingredients and when they are
thrown in a hot furnace the soot usually burns. Quicker action can be had
if they are chopped up.
Before a remover is used, the fire must be put in good condition with a
substantial body of hot fuel on top. Close the ash-pit door and the slots
in the firing door and scatter the remover on the hot coals. Close the
firing doors and at once reduce the draft by partially closing the pipe
dampers. The draft should not be closed so tight as to cause fumes to
escape into the cellar. Let the remover "stew" for 10 to 20 minutes or
until fumes stop rising from the coals; then make the fire burn fiercely
by opening the ash-pit door and the damper. Shaking ashes out will help.
The slots in the firing door can be opened or the door itself set ajar.
If soot in the furnace will not ignite, throw a little wood or paper on
the fire.
Instead of making a special job of cleaning at intervals, one or two cups
of salt may be thrown on the fire once a day with the expectation that
the furnace will produce a high enough temperature to ignite some of the
soot. This is most likely to succeed in cold weather when the furnace
temperatures are high.