Manual Operation; Manual Mode Limited To 5 Minutes - Honeywell Krom Schroder PFU 780 Technical Information

Parameters

4 .8 Manual operation

For convenient setting of the burner or analysing faults.
The parameter display is not available in Manual mode.
Manual mode can be accessed only if the unit was not
in Fault state before switching off. The following times/
functions are not active in Manual mode: start-up at-
tempts, restart, minimum combustion time and cycle
lock.
If the Reset/Information button is pressed for 2 s dur-
ing switch-on, the PFU reverts to Manual mode. Two
dots blink on the display.
In this operating mode, the burner control unit operates
independently of the status of the inputs (apart from
the pre-purge input and the safety interlocks. These are
of higher priority and will be processed first).
Each time after the button is pressed again, the PFU
moves to the next section of the program sequence
and stops there. After approx. 3 s, the flame signal will
be displayed instead of the program parameter. Briefly
pressing the Reset/Information button (< 1 s) displays
the relevant Manual mode step. If there is flame simula-
tion during the start-up, the flame signal is displayed
immediately.
On units with air valve control, the air valve can be
opened and closed repeatedly by pressing the button
during operation.
Manual mode can be terminated by switching off the
PFU (On/Off button).
PFU 780 · Edition 02.12l

4 .8 .1 Manual mode limited to 5 minutes

Parameter 34:
Parameter 34 determines when Manual mode is termi-
nated.
Parameter 34 = 0:
Manual mode is not limited in time. If this function has
been selected, operation of the furnace may be contin-
ued manually in the event of failure of the central con-
trol system.
Parameter 34 = 1:
Manual mode ends automatically five minutes after the
last time the button was pressed. The PFU then moves
abruptly back to start-up position/standby.
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