Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 24

Installation
Electrical Connections
External connections for boiler models 2.5 and 3.0
Legend
sÖA1 Heating circuit pump A1
Heating circuit pump M2
sÖM2
Heating circuit pump M3
sÖM3
sA Circulation pump for tank heating
sK DHW circulation pump
Boiler circuit pump
sL
gÖ Central fault message
gS 3-way mixing valve
gSM2/M3 Mixing valve motor 120 V~
24
(continued)
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
On-site relay
A
B On-site safety equipment
On-site indoor air damper
C
D Feedback contact
Note: To connect feedback contact D, remove jumper
25 L/26 L (factory set condition).