Additional Functions - Siemens KNX RDG400KN Basic Documentation

Air heating/cooling
changeover
K N X
R
Supply air temperature
Water heating/cooling
changeover
K N X
R
Heating/cooling
changeover
Automatic heating/
cooling changeover via
changeover sensor
Changeover switch
Siemens
Smart Infrastructure
3.5

Additional functions

The supply air temperature sent by the primary controller indicates whether cold or
warm air is supplied.
The controller determines the necessity to open or close the air damper according
to the supply air temperature, the room temperature setpoint and the current room
temperature.
If no supply air temperature is available via bus, air changeover is cooling per
default.
With "Single-duct" applications, changeover can also be accomplished via a local
multifunctional input X1-D1 (P38, P42).
Only one input source must be used, either local input X1-D1 or the KNX, and
parameter "Control sequence" must be set to automatic heating/cooling
changeover (P01 = 3).
For functionality of the local changeover input, see below (also refer to section 3.8).
With applications "Single-duct with heating/cooling coil", changeover information of
the heating/cooling coil can be received either via bus or the local multifunctional
input X1-D1 (P38, P42).
Only one input source must be used, either local input X1-D1 or the KNX, and
parameter "Control sequence" must be set to automatic heating/cooling
changeover (P01 = 3) (also refer to section 3.8).
In the absence of the required heating/cooling information from the bus (e.g. due to
problems with data communication, power failure, etc.), the thermostat operates in
the last valid operating mode (heating or cooling).
If a cable temperature sensor (QAH11.1 + ARG86.3) is connected to X1, and
P38 = 2, the water or supply air temperature acquired by the sensor is used to
change over from heating to cooling mode, or vice versa.
· When the water/air temperature is above 28 °C (adjustable via P37), the
thermostat changes over to heating mode. Heating mode is maintained until the
temperature falls below 16 °C (adjustable via P36)
· When the water/air temperature is below 16 °C (adjustable via P36), the
thermostat changes over to cooling mode. Cooling mode is maintained until the
temperature rises above 28°C (P37)
· If the water/air temperature is between the 2 changeover points immediately
after power-up (inside the hysteresis), the thermostat starts in the previous mode
The water/air temperature is acquired at 30-second intervals and the operating
state is updated accordingly.
M
P36 P37
M Operating mode
T Water temperature
w
RDG400KN,RDG405KN Basic documentation
T [°C]
w
Cooling mode
Heating mode
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CE1P3192en
2019-04-12