BCU 480 · Edition 03.16l 48
Parameters
4.7 Air valve control on BCU..L
Parameter 30, Behaviour of the air valve during opera-
tion.
Parameter 31, Behaviour of the air valve during start-up.
Parameter 32, Behaviour of the air valve in the event of
a fault lock-out.
The BCU..L features an adjustable air valve control. The
display shows that purging is currently being carried
out with
P 0
.
A
indicates that the air valve is being ac-
tivated for cooling or heating.
The BCU..L supports the following functions:
– Purge
– Cooling in start-up position/standby
– Switching of the burner between low and high burner
capacity during operation via the air valve
– To start up the burner as intended, external activation
of the air valve can be blocked during start-up (pre-
vents synchronization problems between the BCU
and the central control system).
– Setting the air valve parameters, so that it
– opens with valve V1
– opens with valve V2
– opens once the main burner has reached its operat-
ing position
– Low fire over-run time t
KN
after a controlled shut-
down
4.7. 1 Purge
In the case of multiple burner applications, burners with
mechanical combustion air supply are used. The air for
combustion and pre-purge is supplied by a central fan
controlled by a separate logic. This logic determines the
purging time.
The BCU..L..E1 with adapted power management sup-
ports centrally-controlled pre-purge or post-purge.
The BCU..L is informed that purging is currently being
performed by input 22. It then opens the air valve, re-
gardless of the status of the other inputs (purging has
priority). The display indicates
P 0
.
On BCUs without power management, input 22 and in-
put 5 (safety interlocks) must be activated for purging,
see connection diagrams on pages 14 (BCU 480), 16
(BCU 480..B1) and 18 (BCU 480..P with industrial plug
connector).
4.7. 2 Cooling in start-up position/standby
The air valve can be activated externally via input 23 for
cooling in the start-up position. During activation of the
air valve the display shows
A 0
, indicating that cooling is
currently being carried out.
4.7.3 Burner start
Parameters 30 and 31 determine the behaviour of the
air valve during burner start.
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