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Siemens
RDG400KN,RGD405KN Basic documentation
CE1P3192en
Building Technologies
2017-02-17
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.
P36
M
T
w
[
癈
]
P37
31
91
D
1
24
M Operating mode
Cooling mode
T
w
Water temperature
Heating mode
The QAH11.1 cable temperature sensor for automatic heating/cooling changeover
can be replaced by an external switch for manual remote changeover.
Air heating/cooling
changeover
KNX
R
Supply air temperature
Water heating/cooling
changeover
KNX
R
Heating/cooling
changeover
Automatic heating/
cooling changeover via
changeover sensor
Changeover switch
