83
16. Heating at Low Thermal Output Tula Standard
(during
Transitional
Seasons)
You can vary the thermal output of your Tula by adjusting the
quantity of fuel used.
NOTE!
Do not attempt to slow down the combustion
by reducing the air supply. When heating with
wood, this can result in an incomplete burning
process and pose the risk of an explosive-like
combustion of the accumulated wood gases
(defl agration).
Heating with Wood at Low Thermal Output
Procedure
Position of
Control Elements
Adjust secondary air
Set secondary air slider
to position 3-4
Add two logs weighing
approx. 0.5 kg in total into
the middle of the fi re box
Close fi re box door (fi g. 7)
Tab. 5
17. Emptying the Ash Drawer
As a safety precaution, please make sure that you only dispose
of ashes once they are cold. While the ash collects during the
fi re, the lid (fi g. 9/1) is located under the ash drawer
(fi g. 9/2).
The ash drawer contains the mineral components of the wood
(approx. 1%) as combustion residues.
Remove both the ash drawer (fi g. 10/2) and the lid (fi g. 9/1)
located underneath it. Make sure the ash does not pile up all
the way to the bottom of the fi re box. Slide the lid (fi g. 10/1)
onto the ash drawer so that it is closed; this prevents ashes
from fl ying around, which in turn means your home stays
clean.
1
Fig. 9
2
2
Fig. 10
1
18. The Combustion Process
EA piece of wood burns in three phases. In a wood fi re,
however, these processes occur both consecutively and
simultaneously.
18.1 Drying Phase
The moisture still remaining in the air-dried wood (approx.
15 - 20%) is evaporated. This takes place at temperatures of
approx. 100°C. For the evaporation to occur, the wood must
be supplied with heat during the warming up phase; this is
achieved by using small wood logs.
18.2 Degasifi cation Phase
At temperatures between 100°C and 150°C, the contents of
the wood start - slowly at fi rst – to disintegrate and gasify and
the wood begins its thermal decomposition. At tempera-
tures above 150°C, the gas development accelerates. The
proportion of volatile components makes up around 80%
of the wood substance. The actual combustion begins at a
temperature of about 225°C (ignition temperature) with the
ignition of the resultant gases and the release of heat. There
must be an adequate supply of oxygen available for this
purpose. The peak of the combustion process is reached at
approx. 300°C. The reaction process is now so rapid that the
largest amount of heat is released at this point; fl ames can
reach temperatures of up to 1100°C.
18.3 Burn-off Phase
Glowing charcoal embers remain after the volatile compon-
ents have been burned off. These burn slowly, almost without
fl ames, at a temperature of approx. 800°C.
Crucial to a clean and effi cient combustion process is a
Summary of Contents for Tula
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