ChilliP-A5-Manual-2020-Download

4.e Principles of Combustion

All fuels need the presence of oxygen to burn. The more oxygen a ﬁre gets the hotter

and faster it will burn. When, where and how air is introduced into a ﬁrebox of a stove

will greatly inﬂuence the heat output, burning rate, fuel eciency and impact on the

environment. Dierent fuels burn in dierent ways and it is important to know the

basics in order to operate your multi-fuel stove with conﬁdence.

WOOD

Wood needs to be seasoned (cut and stored for at least one year after cutting) or kiln

dried prior to burning in the stove with a moisture content of less that 25%. As a fuel

it gives a good ﬂame and a reasonably high heat output, the burn rate is high and will

vary considerably depending on size and species. The size of wood logs will vary but a

guideline is given in the tech spec for each model. Wood requires combustion air to be

directed down onto it (down draught) to burn most eciently.

Tips for identifying dry wood

1) Visible cracks at the end of the log

2) Bang two logs together, they will sound hollow

3) Wood moisture content measuring devices are available

There are 3 stages in the burning of wood

stage 1

Drying out. When a piece of wood enters the ﬁrebox it will stay below the boiling point of

water (100°C) until all the moisture has been driven out. Between 150 – 200°C wood begins

to give o volatile gases, some of these will burn while others will mix with the carbon dioxide

and water vapour and be carried out the chimney as smoke.

stage 2

In the second stage of combustion temperatures must reach 600°C for the gases to start

burning o. This will only occur with the right amount of air and heat leading to higher

eciencies. These gases burn as a yellow ﬂame above the wood.

stage 3

Charcoal is left once all the gases have been burnt o. The charcoal contains at least half

of the wood’s heat potential, at this stage the ﬁre will burn more slowly and without ﬂame

requiring less air.