Viessmann VITOCROSSAL 200 Service Instructions Manual page 32

Commissioning, inspection, maintenance
Air pressure switch
& if the idle state check is not suc-
cessful after 5 attempts (anti-cycling
function) (i.e the air pressure switch
contact does not open within 30 s)
& if, during the pre-purge phase, the
minimum flow rate is not produced
(fault shutdown via the anti-cycling
function)
& if, in control mode, the air pressure
switch fails or the air pressure lies
outside the permissible range
Burner control unit
Display and programming unit
Function
A display and programming unit is integrated into the burner control unit. The
display indicates the respective operating conditions, the service and parameter
conditions as well as all fault and error messages.
A Reset key
B LED: Left – heat demand; centre –
flame; right – fault
C Selection key
32
(cont.)
The fault shutdown is indicated with
the fault codes "F AA" and "F AB" in
the burner control unit display. This
can be rectified by pressing reset for
at least ¼ s.
This indicates a serious fault. The
fault shutdown by the air pressure
switch is displayed as a fault in the
control unit.
The air pressure switch is set at the
factory.
This guarantees hygienic combustion.
This will also ensure a minimum pre-
purge, as the air pressure switch still
responds at minimum output.
The display comprises three elements
of seven segments each. Four keys
enable adjustments to be made at the
different operating levels.