Viessmann VITODENS 200-W Installation And Service Instructions Manual page 157

Electronic combustion control unit
Air ratio λ– CO /O
2 2
Air ratio λ
1.20
1.24
1.27
1.30
1.34
1.37
1.40
1.44
1.48
For optimum combustion control, the
system regularly carries out an auto-
matic self-calibration; also after a power
failure (shutdown). For this, the combus-
tion is briefly regulated to max. ionisation
current (corresponding to air ratio λ=1).
Automatic calibration is carried out
shortly after the burner start and lasts
approx. 5 s. During calibration, higher
than normal CO emissions may occur
briefly.
content
O content CO
2 2
(%) (%) for natu-
ral gas E
3.8
4.4
4.9
5.3
5.7
6.1
6.5
6.9
7.3
(cont.)
content CO content
2
(%) for natu-
ral gas LL
9.6
9.2
9.0
8.7
8.5
8.3
8.1
7.8
7.6
Function description
CO content
2
(%) for LPG P
9.2 11.3
9.1 10.9
8.9 10.6
8.6 10.3
8.4 10.0
8.2 9.8
8.0 9.6
7.7 9.3
7.5 9.0
157