EVA MAJOLICA LINE, Инструкция по эксплуатации

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05. DRAUGHT
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Fumes heat up during combustion, increasing their volume. Their density is therefore lower than the one of the surrounding colder
air.
This difference between the inside and outside temperatures of the chimney results in a negative pressure which increases
proportionally to the vent pipe length and the temperature.
The draught must be stronger than the fume circulation resistance so that all exhaust fumes generated during combustion inside the
stove are drawn upwards through the outlet and the vent pipe. Many weather conditions affect the vent pipe functioning, such as rain,
fog, snow, altitude, and wind being the most important since it can create both negative pressure and dynamic loading.
The wind action varies depending on whether it is ascending, descending or horizontal.
•
Ascending wind always results in an increased negative pressure and draught.
•
Horizontal wind results in an increased negative pressure as long as the chimney cowl was properly installed.
•
Descending wind always diminishes the negative pressure, sometimes inverting it.
Excess draught causes an increase in the combustion temperature and consequently a loss in stove efficiency.
A part of the combustion fumes are drawn up through the vent pipe together with small pellet particles before combustion reducing
stove efficiency, increasing fuel consumption and resulting in the emission of polluting fumes.
At the same time the high fuel temperature, due to an excess amount of oxygen, wears down the combustion chamber
sooner than expected.
On the other hand, poor draught slows down combustion resulting in a decrease in the stove temperature, fume spillage inside the
room, a loss of stove efficiency and dangerous build-up in the vent pipe.