barbas ENERGA 80-50, Installation Instructions Manual

Page: 73 / 76

73
ENERGA 80-50
Do I have to take any extra measures if the room I am heating has an extractor fan
(mechanical ventilation)?
If the combustion air comes from the living-room:
A fl ue gas fan is required for permanent extraction of the area in which the fi replace is
placed.
The type of fl ue gas fan depends on the capacity of the extractor system.
Always consult your installation engineer about this.
If the combustion air comes directly from outside via a direct connection:
If there is constant extraction of the room in which the fi re is located, no additional
provisions are necessary.
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 fi re or
burning impregnated or painted wood for example). Creosote ignites at approx. 500°C.
This temperature can easily be reached if the fi re is raging. This means that deposits of
creosote in your chimney could cause a chimney fi re.
What happens when wood is burnt?
The combustion process.
The combustion of wood involves the following steps.
Drying
The fi rst 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 signifi cant 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 fi re 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.