Viessmann VITOGAS 100 Service Instructions Manual page 21

Time chart and function
Function
Pilot gas valve B and, if installed,
external LPG valve C open after a
heat demand A.
Gas flows to the pilot burner; at the
same time the HV ignition D is
switched ON.
The burner control unit receives a
flame signal E via the ionisation
electrode.
(cont.)
After the pilot burner stabilising time
T , main gas valve F opens and
stab
the burner ignites.
Note
A reset after a fault shutdown can only
be implemented after a minimum of 10
seconds.
Ignition system
21