Viessmann Vitocrossal 200 Series Service Instructions Manual page 50

Function description
Air pressure switch
Fan pressure monitoring (air pressure switch 1 - 131)
The switching threshold of air pressure switch 1 (131)
is monitored in all fan ramp-up phases and checked
during modulating burner operation. This ensures a
minimum pre-purge.
The air pressure switch triggers a fault shutdown of the
burner control unit under the following circumstances:
If the static pressure check was unsuccessful after
■
approx. 5 minutes.
■ If the air pressure falls outside the permissible range
during the pre-purge phase (tolerance time approx. 5
minutes).
■ If, in control mode, the air pressure switch fails or the
air pressure falls outside the permissible range.
The fault shutdown is indicated by fault codes "F F5"
and "F F7" on the burner control unit display (see
page 41). The fault shutdown can be cleared by press-
ing reset button R. Check whether a pressure drop
occurs in the ventilation air pipe (e.g. as a result of
blockage or clogged air filter).
Combustion chamber pressure monitoring (air pressure switch 2 - 131A)
To monitor the combustion chamber pressure, the
switching threshold of air pressure switch 2 (131A) is
monitored in all operating phases (except during safety
and stabilising time).
The air pressure switch triggers a fault shutdown of the
burner control unit under the following circumstances:
If the combustion chamber pressure falls outside the
■
permissible range in the pre-purge phase, in control
mode or in the post-purge phase after 2 attempts.
■ For multi-boiler systems with flue gas cascade:
Checking and monitoring of the flue gas damper
function.
The fault shutdown is indicated by fault code "F FB" on
the burner control unit display (see page 35). The fault
shutdown can be cleared by pressing reset button R.
Fan for burner 115 to 311 kW
A
Fig. 40
Connector with screw
A
50
Burner output in kW Setting value in mbar (Pa)
75
87
115
142
186
246
311
Burner output in kW Setting value in mbar (kPa)
75
87
115
142
186
246
311
■ Remove the screw. Attach connecting line. Check for
tightness.
Check control cables:
Connection and kink-free routing
■
Application and seating of retaining clips
■
0.5 (50)
↓
1 (100)
↓
4 (0.5)
↑