Viessmann Vitogas 200-F GS2 Service Instructions Manual page 27

Ignition system
Time chart and function
(cont.)
Function
Pilot gas valve E and external LPG
valve B (if installed) open after a heat
demand A is issued. The gas pressure
switch C (if installed) is switched on.
Gas flows to the pilot burner; at the same
time, ignition D is switched on.
The burner control unit receives an ioni-
sation current F via the ionisation elec-
trode.
After the pilot burner T4 has stabilised,
main gas valves G open and all burner
sections ignite.
Note
A reset after a fault shutdown can only
be implemented after at least 10 s have
elapsed. For this, switch the control unit
ON/OFF switch OFF and ON again.
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