Basic Documentation

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Siemens Universal controllers RMU710B, RMU720B, RMU730B CE1P3150en
Building Technologies Frost protection (basic types A and P) 03.10.2011
17.5 Troubleshooting
17.5.1 Configuration error
The first input with the input identifier is used when multiple inputs are configured
as frost protection inputs with the same identifier frost protection, frost protection
unit 1, frost protection unit 2, or frost protection unit 3.
17.5.2 Errors in operation
 Frost protection unit:
Digital signals cannot be monitored. If signal (= contact open) is missing, the
interpretation is risk of frost so that the plant switches to frost protection mode
 Two-phased frost protection air side "Active DC 0...10 V = 0...15 °C".
If the signal from the frost protection detector is missing, a message is sent and
the plant switches to frost protection mode
 Two-stage frost protection on the water side (passive Ni 1000).
If the signal from the frost protection detector is missing, a message is sent and
the plant switches to frost protection mode.
If the outside temperature signal is missing, the pump runs permanently (see
section 10.2.11 "On" by outside temperature", the setting value must be set to
5 °C)
No. T
ext Effect
3920 Frost Urgent message, with plant stop
3921 Frost protection sensor
error
Urgent message, with plant stop
3922 Frost risk frost 1 Urgent message, with plant stop
3923 Frost risk frost 2 Urgent message, with plant stop
3924 Frost risk frost 3 Urgent message, with plant stop
Fault status messages