129
The electronic combustion controller utilises the physi-
cal correlation between the level of the ionisation cur-
rent and the air ratio
λ
. The maximum ionisation cur-
rent is achieved at an air ratio of 1 for all gas qualities.
The ionisation signal is evaluated by the combustion
controller. The air ratio is regulated to a value that is
between
λ
= 1.2 and 1.5. This range provides for an
optimum combustion quality. Thereafter, the electronic
gas train regulates the required gas volume subject to
the prevailing gas quality.
To check the combustion quality, the CO
2
content or
the O
2
content of the flue gas is measured. The pre-
vailing air ratio is determined using the actual values.
To achieve optimum combustion control, the system
regularly carries out an automatic self-calibration; also
after power failures (shutdown). For this, the combus-
tion is briefly regulated to maximum ionisation current
(corresponding to air ratio
λ
=1). Self-calibration takes
place shortly after the burner starts. The process lasts
approx. 20 s during which higher than normal CO
emissions may occur briefly.
Specification
Electronic combustion control unit
5593201
Service
Summary of Contents for B2HF
Page 33: ...33 2 2x 1 Fig 26 Installation sequence Closing the wiring chamber 5593201 Installation ...
Page 111: ...111 1 2 4 3 6 5 Fig 56 Troubleshooting Repairs cont 5593201 Diagnosis ...
Page 134: ...134 WiFi router 31 Wiring diagram 121 Keyword index Keyword index cont 5593201 ...
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