Viessmann VITOGAS 100 GS1 series Installation Instructions Manual page 34

Wiring Diagrams
Vitogas 100, GS1 Ladder Diagram of Ignition System
Demand for heat causes vent damper
H
blade to open, closing vent damper
end switch ES. 120 V is available to
transformer.
Ignition module is energized with 24 V
H
from the 24 V transformer.
Pilot valve is energized with 24 V.
H
Pilot sparks and pilot gas flows. Once
pilot proves, 24 V is applied to
"MV/PV" and "MV" energizing main
valve.
34
400 ºF / 204 ºC
235 ºF / 113 ºC
Burner cycles on and off in response
H
to operating control (room thermostat,
end switch of zone valve, separate
indoor/outdoor reset control).
Ignition system can cycle off
H
adjustable high limit aquastat in boiler
control during a demand for heat.
Legend
41 Terminals in plug
R Relay coil 1
1R Contact of relay 1
LC Limit contact in boiler control
T 120 V / 24V, class II transformer
F1 Fuse (slow blow)
VD Vent damper
ES End switch in vent damper
FRS Flame roll-out switch
BVS Blocked vent switch
L1 120 V (hot)
N 120 V (neutral)
BVS (blocked vent switch) or FRS
H
(flame roll-out switch) can de-energize
ignition system.
Vitotronic boiler controls and
Vitogas 100, GS1 Service
Instructions