Viessmann FB2B Installation And Service Instructions Manual page 144

Function description
Electronic combustion controller
Air factor λ – CO /O content
2 2
Air factor λ O content (%) CO
2
1.24 4.4
1.27 4.9
1.30 5.3
1.34 5.7
1.37 6.1
1.40 6.5
1.44 6.9
To achieve an optimum combustion con-
trol, the system regularly carries out an
automatic self-calibration; also after a
power failure (shutdown). For this, the
combustion is briefly regulated to max.
ionisation current (equals air factor λ=1).
The 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.
144
(cont.)
content (%) for nat-
2
ural gas H
9.2
9.0
8.7
8.5
8.3
8.1
7.8
CO content (%) for
2
LPG P
10.9
10.6
10.3
10.0
9.8
9.6
9.3