Siemens Synco 200 - Operating principles and settings

10.3 Operating principles and settings
10.3.1 Frost protection unit (DIG)
This picture shows an application with an air- or water-side frost protection unit:
Application example
T
T
DI
3101S22
X1
x
Y
SIGNAL Y
LABEL
FRST
Reliable frost protection depends on correct sensor placement.
Note
If the temperature falls below the set limit value, the frost protection unit sends a
signal to the controller. Meaning:
Frost protection control
functions
• Contact (Q11 - Q14 / terminals 1-3) closed: No frost hazard
• Contact (Q11 - Q14 / terminals 1-3) open: Frost hazard
A frost hazard signal triggers the following actions:
• The fan release relay is deenergized (no release of fan)
• The control loop configured with the air heating coil at risk from frost switches off
all cooling sequences, and opens all heating sequences to 100%. It also
switches on the air heating coil pump.
=> Important: Step switches are also switched on in the process!
• If 2 controllers are configured in the RLU2…, the second (other) control loop is
switched off as well
• The outside air dampers are closed
The frost protection function with frost protection unit is activated in all operating
modes (Comfort, Economy, Protection). Therefore, it also overrides limitations and
disabling as a function of the outside temperature!
Note
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Siemens Universal Controllers RLU2… CE1P3101en
Building Technologies Frost protection (FROST) 29.08.2008