The Combustion Process; Drying Phase; Degasifi Cation Phase; Burn-Off Phase - HASE Toronto Mode D'emploi

14. The Combustion Process

A piece of wood burns in three phases. In a wood fi re, however, these processes take place
both consecutively and simultaneously

14.1 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.
14.2 Degasifi cation Phase
At temperatures of between 100°C and 150°C, the contents of the wood start (slowly at
Fig. 5 The Combustion Process
fi rst) to disintegrate and gasify and the wood begins its thermal decomposition. At tem-
peratures above 150°C, the gas development increases strongly. The proportion of volatile
components makes up around 80% of the wood substance.
At a temperature of about 225°C (ignition temperature), the actual combustion begins
with the ignition of the resulting 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.

14.3 Burn-off Phase

Glowing charcoal embers remain after the volatile components 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 complete (as possible) chemical
reaction of the wood gases with the oxygen in the combustion air. With your Hase stove,
the combustion air is pre-heated and guided into the fi re box via wide air inlet openings,
enabling a good and thorough mixing of the gases with the air. An important variable in any
combustion phase is the amount of combustion air. Not enough air leads to an oxygen de-
Degasifi cation
fi ciency and incomplete combustion, while too much air reduces the fi re box temperature
and thus the effi ciency. Incomplete combustion can generate air pollutants such as dust,
carbon monoxide and hydrocarbons.

14.4 Expansion Noises

Steel expands upon heating and contracts as it cools, which can cause your stove to emit
audible expansion sounds. However, the design and construction of your stove takes this
Drying
into account and prevents this physical process from damaging the stove.

15. The Right Fuel

Only fuels which generate low quantities of smoke may be burned in stoves. For the To-
ronto, only natural, untreated, beechwood logs, including the adherent bark, can be used
Burn-off
as fuel.
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