PFU 780 · Edition 02.12
39
4 .7 .4 Air valve opens in the case of external activation (not
during start-up)
02
00 A000 A0
t
SA2
A8
07
04
t
t
FS2
06
t
SA1
t
Z
t
FS1
03
A
10a
22e
26a
16c
18e
2c–4c
18a
14a
88
10e
26e
30a
28c
2e–4e
6a–6e
V1
1
V2
2
ϑ
1
ϑ
2
2
1
PFU 780
A
P
L1
1
2
SPS
PLC
CPE
ϑ
VR..R
VAG
TZI
2
1
UV
VAS
Parameter 30 = 0:
The air valve opens if it is activated externally by input 30e.
Parameter 31 = 0:
The air valve remains closed during start-up
even if it is activated externally.
These settings are required on burners on which the gas/air
ratio is controlled via a pneumatic link and which also need
to be started at low fire, e.g. on two-stage-controlled burners.
In this case, activation of the air valve during burner start via
input 10a must be prevented.
External control allows switchover between low fire and high
fire during operation.
The air valve can be activated externally via input 10a for cool-
ing the burner in the start-up position/standby.
Parameters > Air valve control PFU . .L