55
Bellfires
English
Instructions for use and installation instructions
Do I have to take any extra measures if the room I am heating has an extractor
fan?
Connect the combustion air intake with a metal (flexible) pipe to the grill in the exterior
wall. The combustion air will then be sucked in from outside the area in which the fire is
located.
What is creosote?
Creosote is a tar-like deposit which is left in the chimney. It is formed in poor
combustion conditions when burning wood (damp wood, pinching off the air supply to
the fire or burning impregnated or painted wood for example). Creosote ignites at
approx. 500°C. This temperature can easily be reached if the fire is raging. This means
that deposits of creosote in your chimney could cause a chimney fire.
What happens when wood is burnt?
The combustion process.
The combustion of wood involves the following steps.
Drying
The first step is that the fuel (wood) dries out. Even at low temperatures (<100°C), any
moisture still in the wood will evaporate. This drying procedure implies a significant loss
of energy if wood which is ‘too’ damp is burnt. The right degree of moisture is achieved
after 1.5 - 2 years of drying. The moisture content is then 15 - 17%.
Decomposition
At moderate - high temperatures (150°C - 350°C), the decomposition process can be
discerned. This is when the chemical structure of the fuel breaks down. This process
involves the creation of volatile compounds such as carbon monoxide (CO), water
vapour (H
2
O) and methane (CH
4
). In addition, substances which are volatile at
decomposition temperature but condense at lower temperatures are often released.
These are the tar-like components (this by-product is also known as creosote, which is
deposited in the chimney and cold parts of the fire in poor burning conditions).
Combustion of the products of decomposition
The volatile compounds burn in the gas phase if O
2
(air) is added. The ignition
temperature of these volatile compounds is approx. 550°C.
Combustion of solid hydrocarbons
The solid component that remains consists of pure hydrocarbons, which will burn at
approx. 800°C if O
2
(air) is added.
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