11
Combustion Air Control
For clean boiler convection surfaces, the flue
gas temperature should be approximately 170
ºC. Raising temperature by increasing power
will reduce the boiler efficiency. Too low
power should not be used either as this will
drop the flue gas temperature below 150 ºC
due to corrosion hazard.
The required air quantity and ratio for burning
varies depending on the wood to be burnt.
Primary and secondary air is factory adjusted
for birch firewood.
Upper primary air does not have to be ad-
justed under normal operating conditions.
Lower primary air should be adjusted when
the boiler power needs to be changed. The
boiler power grows in correlation with the
flame length.
Secondary air can be adjusted when the boiler
water temperature has been unchanged for 45
minutes after the beginning of combustion.
Upper
primary air
Lower primary
air
Lower seconda-
ry air
