17
SEQUENCE OF OPERATION
Switching times are given in seconds, in the burner
startup sequence.
Legend for the times
t1
Pre-purge time with air damper open.
t2
Safety time.
t3
Pre-ignition time, short (“Z” connected to
terminal “16”).
t4
Interval between voltage at terminals “18” and “20”
t5
Air damper running time to OPEN position.
t6
Air damper running time to low-flame position
(MIN).
t7
Permissible after-burn time.
t8
Interval to the OPEN command for the air damper.
LAL 2.25
t1
t2
t3
t4
18
4
2
12
t5
t6
t7
t8
optional
optional
12
4
(A)
D2870
Siemens LAL control