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organized at low CO content in the flue gases as well as low air excess
ratio) should be saturated yellow and the edges of the flame should be
blue colored.
In case that the colour of the flame is:
•
Saturated red – this shows that there is deficiency of secondary air – it
is required to increase the secondary air flow rate by opening the total
air flow rate control flap (driven by the thermovalve);
•
Light yellow or with short length – this indicates, that there is excess
of secondary air and the secondary air flow rate should be decreased
by closing the total air control flap – adjust the thermovalve, which
controls that flap;
•
The flame has low intensity (so called “lazy flame”) – this shows that
the primary air flow rate should be increased – it is necessary to open
the primary air control flap by pulling the axes of that flap;
•
Smoke in the flame – this shows that there is absence of secondary air
and increased intensity of volatile gases as well as tar release
rate.That’s why it is necessary to decrease the primary air flow rate
and to increase the secondary air flow rate – in order to do that, one
should close the primary air control flap by pushing it. The effect of this
adjustment will be seen in a period of at least 15 minutes, so one has to
be patient and wait. The change of the axis position should be done in
small steps, as this adjustment is highly sensitive;
The criteria for optimal combustion is the operating conditions of the
ceramic element, positioned in the combustion chamber of the boiler – the
outer surface of the ash layer should be light-grey by color, the quantity of
the deposited ash should be relatively small, no unburned charred particles
should be seen (chars are dark colored particles).
The quality of the adjustment of the combustion process could be estimated
by monitoring the color of the flue gases, released out of the chimney,
which is connected to the boiler. In case that the flue gases are dark
colored, that is sign for deficiency of secondary air and/or the fuel quality
is not covering the requirements (most often the moisture content is higher
than required).
The flue gases, emitted in the atmosphere from the chimney, could
eventually change the transparency of the air, thus the flue gases presence
could be recognized, even light refraction could be observed at high
difference of the temperature of the flue gases and the temperature of the
ambient atmosphere. The products of the combustion process (mainly
water vapor H
2
O and carbon dioxide – CO
2
) are not visible. However, at
