6.4
Exhaust System
Wood smoke can condense inside the chimney, forming a inflammable deposit called creosote.
If creosote builds up in the system, it can ignite when a hot fire is burned in the stove. A very
hot fire can progress to the top of the chimney. Severe chimney fires can damage even the best
chimneys. Smouldering, smoky fires can quickly cause a thick layer of creosote to form. When
the stove is operated properly, the exhaust from the chimney is mostly clear and creosote builds
up more slowly.
«Creosote - Formation and Need to Removal
When wood is burned slowly, it produces tar and other organic vapors, which combine with
expelled moisture to form creosote. The creosote vapors condense in the relatively cooler
chimney flue of a slow-burning fire. As a result, creosote residue accumulates on the flue
lining. When ignited this creosote makes an extremely hot fire.
The chimney connector and chimney should be inspected at least once every two months
during the heating season to determine if a creosote buildup has occurred.
If a significant layer of creosote has accumulated (⅛" [3 mm] or more) it should be removed
to reduce the risk of a chimney fire.»
6.5
Frequency
It is not possible to predict how much or how quickly creosote will form in the chimney. It is
important, therefore, to check the build-up in the chimney monthly until the rate of creosote
formation is determined. Even if creosote forms slowly in the system, the chimney should be
cleaned and inspected at least once each year.
Establish a routine for the fuel, wood burner and firing technique. Check daily for creosote
build-up until experience shows how often you need to clean to be safe. Be aware
that the hotter the fire the less creosote is deposited, and weekly cleaning may be necessary in
mild weather even though monthly cleaning may be enough in the coldest months. Contact your
local municipal or provincial fire authority for information on how to handle a chimney fire. Have
a clearly understood plan to handle a chimney fire.
6.5.1
Sweeping the Chimney
Chimney sweeping can be a difficult and dangerous job. People
with no chimney sweeping experience will often prefer to hire
a professional chimney sweep to inspect and clean the system
for the first time. After seeing the cleaning process, some will
choose to do it themselves.
The chimney should be checked regularly for creosote build-up.
Inspection and cleaning of the chimney can be facilitated by
removing the baffle. See
Installation»for more details.
Page 28
«Appendix 9: Air Tubes and Baffle