Viessmann Vitocrossal 200 Service Instructions For Contractors page 50

Function description
Air pressure switch
Fan pressure monitoring function (LDW1)
B
Fig. 53
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)
B
Fig. 54
To monitor the combustion chamber pressure, the
switching threshold of air pressure switch 2 (LDW2) is
monitored in all operating phases (except during safety
and stabilising time).
50
A
C
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 regular operation or
the air pressure lies outside the permissible range
The fault shutdown is indicated by fault codes "F F5"
and "F F7" in the burner control unit display (see
page 31). The fault shutdown can be cleared by press-
ing reset button .
B
Burner output in LDW1 setting value in mbar (Pa)
kW
87
115
142
186
246
311
Air pressure switch C triggers a fault shutdown at the
burner control unit under the following circumstances:
■ 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 31). The fault
shutdown can be cleared by pressing reset button
Burner output LDW2 setting value in mbar (kPa)
in kW
87
115
142
186
246
311
0.5 (50)
↓
1 (100)
↓
.
B
5 (0.5)
↓