Additional Functions - Siemens RDU341 Basic Documentation

Air heating / cooling
changeover
K NX
R
Supply air temperature
Automatic heating /
cooling changeover via
changeover sensor
Changeover switch
Siemens
Building Technologies
3.5

Additional functions

The supply air temperature sent by the primary controller indicates whether cool 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, then the air changeover is cooling
per default.
With application "Single duct", the changeover can also be accomplished via a
local multifunctional input X1/X2 (parameter P38, P40).
Only one input source must be used, either local input X1/X2 or KNX, and
parameter "control sequence" must be set to automatic heating / cooling
changeover (parameter P01 = 3).
Functionality of the local changeover input see below.
See also section 3.8.
If a cable temperature sensor (QAH11.1 + ARG86.3) is connected to X1 / X2, and
parameter P38 / P40 is = 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 (parameter P37), the thermostat
changes over to heating mode, and to cooling mode when below 16 °C (parameter
P36).
If the water / air temperature is between the 2 changeover points immediately after
power-up, the thermostat starts in heating mode.
The water / air temperature is acquired at 30-second intervals and the operating
state is updated accordingly.
M Operating mode
T Water temperature
w
The QAH11.1 cable temperature sensor for automatic heating / cooling changeover
can be replaced by an external switch for manual, remote changeover:
The sensor or switch can be connected to input terminal X2 or X1, depending on
the commissioning of the inputs (P38, P40).
See also section 3.8.
RDU341 Basic Documentation
Cooling mode
Heating mode
Contact open à heating mode
Contact closed à cooling mode
23 / 68
CE1P3172en
2015-06-08