Siemens Synco 200 Basic Documentation page 139

Application example
Note
Temperature drops
below starting point
Actions if temperature
drops below limit value
Siemens
Building Technologies
10.3.3 2-stage frost protection on the air side (DC 0...10 V)
This picture shows an application with 2-stage, air-side frost protection:
AI
Reliable frost protection depends on correct sensor placement!
If the temperature falls below the set starting point (= limit value + 2 K + P-band),
the following actions are triggered:
All heating sequences are steplessly opened and all cooling sequences are
•
steplessly closed
The air heating coil pump is switched on
•
The purpose is to prevent the temperature from falling below the "frost hazard" limit
value (SET-ON).
If the temperature still drops below the above limit value, the following actions are
triggered:
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 the air heating coil pump on.
=> Important: Step switches are switched on as well!
If 2 controllers are configured in the RLU2..., the second (other) control loop is
•
switched off as well
The outside air dampers are closed
•
Universal Controllers RLU2...
Frost protection (FROST)
X1
LABEL
FRST
x Y
T
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CE1P3101en
29.08.2008