SENKO fireplaces
–
Instruction manual
8
1.3.2. CHIMNEY FUNCTION
Among all the meteorological and geographical factors that influence the
chimney function (rain, fog, snow, insolation period, etc.)
the wind is most
certainly the crucial one
. Apart from the pressure caused by the
temperature difference between the flue gases and the outer chimney air,
there is another type of pressure
–
wind dynamic pressure.
Ascending wind
ALWAYS has the
effect of increasing the pressure
,
i.e.,
underpressure (flue draught)
, provided the chimney is properly
installed.
Descending wind
ALWAYS has the
effect of decreasing the
draught
overpressure occurs. Apart from wind direction and velocity,
chimney position in relation to the house roof and surrounding area is also
important (
figure 2
).
figure 2
wind
Un
favorable
position
Favorable
position
Horizontal wind
8 m/s
underpressure of
30 Pa
Descending wind
under
45
angle and 8 m/s
overpressure of 17 Pa
Flue
gases
from the
fireplace
High (positive)
pressure zone
OVERPRESSURE
Low (negative)
pressure zone
UNDERPRESSURE
