Viessmann VITOTRONIC300 Installation And Service Instructions Manual page 121

Vitotronic 300, GW2B Installation and Service
Connection and Wiring Diagram, Type GW2B
PCB 120V~
Legend
sÖ Heating circuit pump
or
Primary pump, primary store system
or
Circulation pump, flue gas/water heat exchanger
or
Switching output
sA Circulation pump for DHW tank heating (accessory)
DHW recirculation pump (on site)
sK
Shunt pump or boiler circuit pump (on site)
sL
fÖ Power supply, 120V/60 Hz
fA Oil/gas burners
Output for multiple fault messages
gÖ
gS Motor for 3-way mixing valve, return temperature
control
or
Motor for 3-way mixing valve, primary store system
(Optional accessory, not used)
(continued)
lÖ Burner stage 2/modulating
abÖ External connections (remove jumper when
connecting)
a External safety equipment
b External blocking
Safety chain (potential -free)
abA
Power supply connection for accessories
abH
F1, F2 Fuse
F6 Fixed high limit "E"
F7 Adjustable high limit
K1-K10 Relay
S1 ON/OFF switch
S2 TEST key
X Electrical interfaces
Designs
121