Viessmann VITODENS 343-F WS4A Installation And Service Instructions Manual page 63

Further details regarding the individual steps
Maximum collector temperature CX
Delivered condition: CX 120.0
Setting Description
range
CX 100.0 The solar circuit pump is switched ON (collector cooling) when
CX 190.0 this temperature (solar circuit idle, maximum cylinder temperature
has been reached) is exceeded.
For this, the cylinder temperature can exceed the maximum cylin-
der temperature "SX", but no higher than 90 ºC (safety shutdown).
Minimum collector temperature CN
Delivered condition: CN 10.0
Setting Description
range
CN -10.0 Minimum starting temperature that must be exceeded before the
CN 90.0 solar circuit pump can start. This prevents the pump starting too
frequently.
This function is disabled at CN = 10 ºC.
-10.0 to + 9.9 ºC for frost protection
10.1 to 90 ºC for minimum temperature function
Maximum cylinder temperature FN
Delivered condition: FN 1
Setting Description
range
FN 0 Maximum cylinder temperature control disabled; the solar circuit
pump is controlled in accordance with the selected starting and
stopping temperature differential
FN 1 Maximum cylinder temperature control enabled
FN 2 Maximum cylinder temperature control disabled; return cooling
function enabled
FN 3 Maximum cylinder temperature control enabled without priority;
collector cooling function enabled
Commissioning, inspection, maintenance
120 °C
10 °C
(cont.)
63