Cylinder charging
The function is started when, in the charging release time, the cylinder value falls be-
low the target value by more than 5 K. If parallel cylinder charging has been pro-
grammed, the mixer circuit in the VR 70 remains in operation. The cylinder charging
ends when the preset target cylinder value has been reached. The target cylinder val-
ue therefore corresponds to the cylinder charging switch-off temperature.
Cylinder charging if the cylinder is downstream of the low loss header
The cylinder temperature sensor is connected to the VR 70. The VR 70 takes the "Tar-
get cylinder temperature" set on the VRC 700, adds the value saved under "Cylinder
boost offset" and uses this total to generate the "Target flow temperature for cylinder
charging" value. If the current temperature of the cylinder is 5 K or more below the tar-
get value, the VR 70 activates the charging pump. The value calculated as the "Target
flow temperature for cylinder charging" is now assigned to "Forced Mode" on the boiler.
The controller sets the boiler to "Cylinder charging mode", sets the target flow tempera-
ture, switches the diverter valve inside the boiler (if installed) to the "Heating" position
and switches on the integrated heating pump. The boiler now adjusts the desired flow
temperature for as long as "Forced Mode" remains active. Once the target cylinder
temperature has been reached, "Forced Mode" stops, the unit goes back to Normal
operating mode and the charging pump that was activated by the VR 70 switches off
once the time set under "Charging pump overrun time" has elapsed.
Anti-legionella function
With this function activated, the cylinder and the connected hot water pipes are heated
to a temperature of 70 °C once a day or once a week. To this end the cylinder target
value is raised to 70 °C and the circulation pump switched on.
The function is stopped when the cylinder temperature sensor measures a temperature
greater than 60 °C for longer than 60 minutes or once 120 minutes have elapsed (to
prevent the system from "getting stuck" in this function if water is drawn at the same
time).
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