Viessmann VITOCROSSAL 200 CM2 Service Instructions For Contractors page 58

Functions
Air pressure switch
Fan pressure monitoring function (LDW1)
A
B
Fig. 41
The switching threshold of air pressure switch 1
(LDW1) is monitored in all fan ramp-up phases and
checked in modulating burner operation. This ensures
a minimum pre-purge.
Air pressure switch triggers a fault shutdown at the
A
burner control unit under the following circumstances:
Combustion chamber pressure monitoring function (LDW2)
C
B
Fig. 42
To monitor the combustion chamber pressure, the
switching threshold of air pressure switch 2 (LDW2) is
monitored in all operating phases (except during the
safety and stabilising time).
Air pressure switch triggers a fault shutdown at the
C
burner control unit under the following circumstances:
58
If the static pressure check was unsuccessful after
■
approx. 5 minutes
■ If the air pressure is outside the permissible range
during the pre-purge phase (tolerance time approx. 5
minutes)
■ If the air pressure switch fails in control mode or the
air pressure lies outside the permissible range
The fault shutdown is shown with fault indicators
"F F5" and "F F7" on the burner control unit display
(see page 34), and can be cleared by pressing reset
button .
B
Rated heat- Rated heat in-
ing output put
P Q (H ) [net
max max i
(50/30 °C) cv]
in kW
400
500
620
If the combustion chamber pressure is outside the
■
permissible range in the pre-purge phase, in control
mode or in the post-purge phase after 2 attempts
The fault shutdown is indicated by fault code "F FB" in
the burner control unit display (see page 34). The fault
shutdown can be cleared by pressing reset button
Rated heat- Rated heat in-
ing output put
P Q (H ) [net
max max i
(50/30 °C) cv]
in kW
400
500
620
Note
Check control cables:
■ Connection and kink-free routing
Fixing and firm seating of retaining clips
■
LDW1 setting
in kW in mbar (kPa)
381
474 2 (0.2)
593
B
LDW2 setting
in kW in mbar (kPa)
381
474 5 (0.5)
593
↑
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