Viessmann SCU345 Manual page 13

System 3
2-tank solar system with pump logic
The controller compares the temperature at sensor
S1 to the temperatures at sensors S2 and S4. If the
measured temperature differences are higher than
the adjusted switch-on temperature differences, the
pump (R1 and/or R2) will be activated and the cor-
responding tank will be loaded up to the adjusted
maximum temperature at most.
Sensor/
Designation Description
terminal
S1 TCOL Temperature collector
S2 TST1B Temperature tank 1 bottom
S3 Optional sensor for measure-
ment purposes or options
S4 TST2B Temperature tank 2 bottom
S5 Optional sensor for measure-
ment purposes or options
V40
Relay Description
R1 Solar pump tank 1
R2 Solar pump tank 2
R3 optional:
Thermal disinfection
R4
Parallel relay
Heat dump
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