15
C. CHIMNEY
The performance of the Compact C-4 stove depends on:
a) The chimney
b) The way it operates
c) The quality of fuel used
After several years of use you may change the type of fuel
used but once the chimney has been installed it can not be ea-
sily changed. Therefore the following information may help you
decide whether to use the existing chimney or to build a new
one.
This information will help you to make the correct decision.
1. How chimneys work
Some basic knowledge about the way chimneys work will
help you get the maximum performance of your stove. The func-
tion of a chimney is:
a) To take the smoke and fumes out of your house without
any risk.
b) To produce enough draught in the stove to keep the fire
burning.
What is the draught?
This is the tendency of hot air to rise.
When the Compact C-4 is lit the hot air rises up the chimney
and goes outside the house. The chimney heats up and keeps
the draught flowing. The draught will not flow properly until the
stove and the chimney are hot.
The draught is affected by the location, size and height of the
chimney.
The following points should be taken into account:
Chimneys inside the house are warmer and maintain a bet-
ter draught.
The suggested size of the chimney will give a good draught.
The height of the chimney affects the draught, the higher the
chimney the better the draught.
The chimney should be at least 1 metre above the highest
part of the roof.
There are other factors which affect the draught.
Trees and high rise buildings near your house.
Wind speed. Generally continuous strong winds increase the
draught but stormy weather reduces the draught.
The outside temperature. The colder the weather the better
the draught.
The barometric pressure. On rainy, damp or windy days the
draught is generally weak.
The intensity of the fire. The hotter the fire the stronger the
draught.
Cracks in the chimney, air inlets through a piping joint, other
devices connected to the chimney etc. can impair the draught.
2. Soot formation and cleaning.
When wood is slowly burnt tar and other organic vapours are
formed which when combined with air humidity form soot. Soot
vapours can condense if the chimney walls are cold. If the soot
catches fire then very high flames are produced. Any accumu-
lation of soot has to be cleaned.
As the accumulation of soot depends on so many different
things it is very difficult to say when the chimney has to be cle-
aned.
A visual inspection is the only sure way to tell whether your
chimney is free from soot.
So, please install your stove so as to give you easy access
to the chimney.
3. Options
There are two ways to build a chimney for your Compact C-
4 stove:
a) A brick work chimney
b) A pipework flue
Studies have shown that there is little difference in their per-
formance regarding the strength of the draught. The ultimate
choice rests with the owner, depending on the type of dwelling.
Whenever possible situate your chimney inside your house.
This way there will be a better draught, less soot and it will last
longer.
The advantages of brick work chimneys are:
a) With bricks and tiles the smoke stays warmer longer.
b) The heat absorbing characteristics of bricks allows you to
keep your house warm for longer after the fire has gone out.
c) It can be built to the owner’s taste.
d) If well built they can be more fire resistant than metal
chimneys.
Brick chimneys should be well lined to keep the smoke hot.
They should be built using corrosion proof high temperature
resistant materials.
As their size is the most important factor they can be round,
square etc.
Brick chimneys for the Compact C-4 should comply with the
measurements stated in section (9) TECHNICAL INFORMA-
TION.
The advantages of pipework flues are:
a) Easy installation
b) They allow slight changes in the pipework routing giving
greater flexibility in choosing the chimney location.
c) Round elbows give a better draught than angular shaped
ones.
4. Rules
The following is a list of rules to be followed when building a
chimney:
a) Always use fire resistant and non inflammable material.
Do not use cement fibre piping for the first two or three meters.
b) Choose the most vertical and straight route possible. Do
not connect several appliances to the same chimney.
