Draft Conditions In The Chimney - Heta SCAN-LINE SOLID C Operating And Installation Instructions

1.9 Draft conditions
and the chimney
Poor draft will not allow the stove to burn, as it
should. The glass can soot, requires cleaning of
the chimney more often, smoke can escape out
when the door is open and it gives poor fuel ef-
ficiency. Leading to unnecessary polluting of the
environment.
Good draft will allow the stove to achieve op-
timal combustion and the highest possible ef-
ficiency. Heta wood stoves are constructed so
that it itself provides an optimal blend of com-
bustion air. This provides a high efficiency/heat,
clean glass and low environmental impact.
Minimum chimney draft for Prestige insert is 10
PA. It is the draft that the stove has been tested
and approved on. The minimum draft is neces-
sary to provide clean burning, beautiful flame
picture, as well as achieving the rated efficiency.
There is a risk of smoke escaping into the room
if the door is opened during vigorous firing, or if
there is a lack of air supply to the room, for ex. if
an extraction fan is in use.
Flue gas temperature at the rated output is 312°C
relative to 20°C. Flue gas flow is 6,3 g / sec.
The chimney height and diameter, as well as
the temperature difference between the flue gas
and outside temperature generates the chimney
draft. Chimney insulation is therefore important
as new efficient stoves create lower flue tempe-
ratures. Wind and weather conditions also in-
fluence draft, in some cases it may be disad-
vantageous wind direction, combined with the
position of the chimney can cause negative draft
(it blows through the chimney), causing smoke
escape from the stove.
Before using after a long period of inactivity,
check that the chimney is free for any blocka-
ges. (soot build-up, bird nests, leaves etc.).
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Combustion
air
Reduced draft can occur when:
• The temperature difference is too small
between smoke gasses and outdoor
• To short of a chimney
• The outside temperature is high, and indoor
temperature is low f. ex. in summer
• False air in the chimney
• Chimney is blocked
• Air tight house (lack of combustion air supply)
• Poorly placed chimney for the surroundings,
for ex. the ridge and trees may cause
turbulence.
Good draft occurs when:
• The difference in temperature in the chimney
(warmer) and outside temperature (colder)
• It is clear weather
• The chimney has the right height min 4 meters
above the stove, and clear of the roof ridge
Combustion
air
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