Viessmann Vitocrossal 300 CU3A 26 Installation Instructions Manual page 40

Control Connections
Connections
(continued)
Pump modulation connection (0-10VDC)
Pump modulation signal can only be applied to output 20
when used as heating circuit pump A1.
Note: See wiring diagram on page 57 for connection
to the control base.
Legend
A Power/pump connection interface
B CU3A Boiler Control
C Variable speed pump with 0-10VDC input signal
for pump modulation
Outdoor Temperature
The chart is based on coding address E6 adjusted to 100.
Note: Minimum pump modulation rate 30% (3VDC).
40
Vitocrossal 300 CU3A 26 to 199 Installation
Relevant Coding Address
A3 Heating circuit pump logic based on outdoor temp.
A5 Heating circuit pump logic based on outdoor
temperature relevant to room temperature setpoint
B5 Heating circuit pump logic based on outdoor
temperature relevant to room temperature setpoint
using room temperature feedback
E5 Heating circuit A1 pump modulation signal activation
- allowing access to coding addresses E6 thru E9
make required adjustments to addresses E6 thru E9
and return coding address E5 to 0, Leaving coding
address E5 set to 1 will generate the C7 fault
E6 Set pump maximum speed up to 100%
E7 Set pump min. speed (min. pump speed is 30%)
E8 Force pump to operate at minimum pump speed
(address E9) during reduced heating mode operation
E9 Min. pump speed during reduced heating operation
Setting of address A3, A5, and B5 will determine shut off
point for pump based on outdoor temperature and/or room
temperature set point.
Pump speed control based on the Wilo-Stratos PARA.
Boiler output voltage (VDC)
Voltage level Description
0V to 0.5V Cable break detected pump
runs on lowest speed
0.5V to 1V Pump standby
1V to 3V Pump runs at lowest speed
2V to 3V Pump runs at Lowest speed
(pump startup)
3V to10V Linear speed presetting
between lowest and
highest speed
Pump speed
30%
0%
30%
30%
30%-100%