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3.5
Additional functions
Heating / cooling
changeover via bus
The heating / cooling changeover information can be received via bus. This is only
possible if the control sequence is set to automatic heating / cooling changeover
(parameter P01 = 3) and no local input X1, X2, D1 is assigned with this function.
K NX
In the absence of the required information (e.g. due to problems with data
communication, power failure, etc.), the thermostat operates in the last valid room
operating mode (heating or cooling).
R
Heating/cooling
changeover
Automatic heating /
cooling changeover via
changeover sensor
If a cable temperature sensor (QAH11.1 + ARG86.3) is connected to X1 / X2, and
parameter P38 / P40 is =2, the water temperature acquired by the changeover
sensor is used to change over from heating to cooling mode, or vice versa. When
the water temperature is above 28 °C (parameter P37), the thermostat changes
over to heating mode, and to cooling mode when below 16 °C (parameter P36).
If the water temperature is between the 2 changeover points immediately after
power-up, the thermostat starts in heating mode.
The water temperature is acquired at 30-second intervals and the operating state is
updated accordingly.
M
16
M
Tw[°C]
28
Cooling mode
Operating mode
Tw Water temperature
Changeover switch
Heating mode
The QAH11.1 cable temperature sensor for automatic heating / cooling changeover
can be replaced by an external switch for manual, remote changeover:
X2
M
T
QAH11.1
X2
M
3076Z03
Contact open  heating mode
Contact closed  cooling mode
T °C
The sensor or switch can be connected to input terminal X2 or X1 or D1 (switch
only), depending on the commissioning of the inputs (P38, P40, P42).
See also section 3.9 “Multifunctional input”.
Manual heating /
cooling changeover
If manual heating / cooling changeover is commissioned (P01 = 2), then heating /
cooling mode cannot be changed via bus / changover sensor / switch; it will remain
in the last mode as selected locally via button.
External / return air
temperature sensor
The thermostat acquires the room temperature via built-in sensor, external room
temperature sensor (QAA32), or external return air temperature sensor (QAH11.1)
connected to multifunctional input X1 or X2.
Inputs X1 or X2 must be commissioned accordingly. See section 3.9 “Multifunctional input”.
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Siemens
Building Technologies
RDG100KN Basic documentation
Functions
CE1P3191en
22 Jun 2010