BCU 370 · Edition 01.19
59
Parameters
4 .6 .5 Post-purge time t
PN
Parameter 19
88
ϑ
t
21
24
1
16
3
30
29
31
13
19-20
4
V1
6
V3
5
V2
17-18
11
DG
max.
9
32
DG
min.
7
DL
90
➔
0
0
➔
90
08
P9
A0
t
PN
00
Determines how long air will be supplied to the com-
bustion chamber after burner operation has been ter-
minated.
To remove combustion gas residues from the burner,
this can be purged with air after operation.
The post-purge time t
PN
starts to elapse once the start-
up signal (
ϑ
) has been deactivated or once the first
safety time has elapsed in case of a safety shut-down.
If the actuator is located above the Ignition position at
this time, it moves to the Ignition position. If it is below
the Ignition position, the actuator stays in its current
position.
Pre-purge on each start-up (parameter 06 = 1):
The actuator moves to the Closed position after the end
of the post-purge time t
PN
.
Quick start (parameter 06 = 0) or pre-purge time = 0
(parameter 18 = 0):
After the post-purge time t
PN
has elapsed, the actuator
moves to the Open position and then to the Ignition po-
sition (parameter 28 = 0) or the Min position (parameter
28 = 1).
If tightness control is activated (BCU..D3, parameter
24 = 3) and quick start is activated (parameter 06 = 0),
the post-purge time must be set to at least the value of
the test period (parameter 26).