Siemens SQN72 Series Manual page 18

Circuit diagrams (examples)
No. E  LAL / LFL / LGK16 / LOK16
2-stage or modulating operation  prepurging at high-fire position (NL)
18/20
Smart Infrastructure
*) Thermostat or similar unit with
changeover contact or 3-position
controller for OPEN/CLOSED
positioning pulses and neutral
position
**) In case of modulating operation,
fuel valve 'BV2' is replaced by a
gas control valve 'RV'
X1 Plug-in space, 4-pole
X2 Plug-in space, 5-pole
X3 Plug-in space, 3-pole
F Internal fuse
Cam disks:
I red
II blue
III
orange
IV black
V green
Program sequence diagram
shows modulating operation.
CC1N7802en
8/11/2021