Installation and operating instruction
Oil burner WL20/2-C Z
7 Commissioning
83307702 1/2019-04 La
38-80
7.4 Check combustion
Determine excess air
Slowly close air damper(s) in the relevant stage until the combustion limit is
reached (smoke number approx. 1).
Measure and document O
2
content.
Read air number (λ).
Increase air number to ensure sufficient excess air:
by 0.15 … 0.2 (equates to 15 … 20 % excess air),
by more than 0.2 for more difficult conditions, such as:
dirty combustion air,
fluctuating intake temperature,
fluctuating chimney draught.
Example
λ + 0.15 = λ*
Set air number (λ*), do not exceed CO content of 50 ppm.
Measure and document O
2
content.
Check flue gas temperature
Check flue gas temperature.
Ensure that the flue gas temperature complies with the data provided by the
boiler manufacturer.
If necessary adjust flue gas temperature, e g.:
Increase burner capacity in partial load to avoid condensation in the flue gas
ducts, except on condensing units.
Reduce burner capacity in full load to improve efficiency.
Adjust heat exchanger to the data provided by the manufacturer.
Determine flue gas losses
Drive to full load.
Measure combustion air temperature (t
L
) near the air damper(s).
Measure oxygen content (O
2
) and flue gas temperature (t
A
) at the same time at
one point.
Determine flue gas losses using the following formula:
q
A
=
(t
A
- t
L
) (
A
2
21- O
2
) + B
q
A
Flue gas losses [%]
t
A
Flue gas temperature [°C]
t
L
Combustion air temperature [°C]
O
2
Volumetric content of oxygen in dry flue gas [%]
Fuel factors
Fuel oil
A2
0.68
B
0.007
