Further Details Regarding The Individual Steps - Viessmann Vitocrossal 200 CM2 400 Service Instructions Manual

Vitocrossal 200, CM2 400, 500, 620 and 620 TX Service

Further Details Regarding the Individual Steps

Fan pressure monitoring function (air pressure switch 1)
The switching threshold of air pressure switch 1 (APS1)
is monitored in all fan ramp-up phases and checked in
modulating burner operation. This minimizes pre-purge.
Air pressure switch A triggers a fault shutdown of the
burner control unit under the following circumstances:
■ If the idle state check is not successful after
approximately 5 minutes.
■ If, during the pre-purge phase, the air pressure
is outside the permissible range (tolerance time
approximately 5 minutes).
■ If, during operation, the air pressure switch fails or
the air pressure is outside the permissible range.
The fault shutdown is shown with fault display "F F5"
and "F F7" on the burner control unit (see page 48) and
can be rectified by pressing reset button R B.
Boiler model
Air Pressure Switch 1 Adjustment Value
in mbar ("w.c.)
400
500
620
620 TX
Note: The air pressure switch is a normally open contact
that closes when pressure rises above its setpoint.
Once the contact closes it will trigger a safety
shutdown of the burner.
1
(0.4 "w.c.)
Combustion chamber pressure monitoring
(air pressure switch 2)
To monitor the combustion chamber pressure, the
switching threshold of air pressure switch 2 (APS2)
is monitored in all operating phases (except safety and
stabilizing times).
Air pressure switch C triggers a fault shutdown of 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 shown with fault display "F Fb"
on the burner control unit (see page 49) and can be
rectified by pressing reset button R B.
Boiler model Air Pressure Switch 2 Adjustment Value
in mbar ("w.c.)
400
500
620
620 TX
Air pressure switch setting example shown
Burner Service
5
(2.0 "w.c.)
31