Siemens Desigo RXB, Technical Manual, Page: 269 / 476

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Siemens RXB (KNX) application library FNC Description of functions for FC-10, FC-11, FC-12 CM110385en_05
Building Technologies Room operating modes 28 Feb 2009
5 Room operating modes
5.1 Description
The room operating modes available with DESIGO RXB are Comfort, Precomfort,
Economy and Protection. In addition, there is a frost protection limit, at which, for
example, an alarm can be triggered. Each room operating mode has separately
adjustable heating and cooling setpoints.
Heating Cooling
Y [%]
100
0
TR
10
3
85D
01
Comfort
Precomfort
Economy
Protection
Frost limit
Y
Output signal (valve or damper actuator)
TR Room temperature
Comfort is the room operating mode in an occupied room. In this mode, the room
temperature is within the comfort range. The room controller operates in the heating or
cooling sequence with the resulting
Comfort setpoints.
In
Precomfort mode (in a vacant room), the controller operates with setpoints slightly
below the Comfort setpoint in heating mode, and slightly above the Comfort setpoint in
cooling mode.
In rooms that are unoccupied for any significant length of time (e.g. night setback based
on a time scheduler (see pages 37, 49, and 59), the supply of energy to the room can
be reduced substantially. In
Economy mode, the controller operates with a setpoint
slightly below the Precomfort setpoint in heating mode, and slightly above the
Precomfort setpoint in cooling mode.
If the building is unoccupied over a long period of time (e.g. holidays) the temperature
setpoints can be reduced (or, in the case of cooling, raised) so that only sufficient
heating or cooling energy is provided to protect the building fabric and its contents.
If the room temperature or return air temperature falls below the
Frost limit , an alarm is
initiated for further processing in the building automation and control system.
The room controller will continue to operate at the relevant setpoint (e.g.
Protection ,
Economy , etc.).
The alarm threshold in the controller is a fixed 5°C. In the case of applications
incorporating an outside air damper, the value can be preset in the range 2 … 10°C.
Comfort
Precomfort
Economy
Protection
Frost limit