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Siemens RDF800KN.., RDF800KN/VB, RDD810KN/NF Basic documentation CE1P3174en
Smart Infrastructure 2020-02-21
3.5 Additional functions
The heating/cooling changeover information can only be received using the bus, if
the control sequence is set to automatic heating/cooling changeover (P01 = 3), and
no local input X1/X2 is assigned with this function.
When the required information is missing (e.g. due to problems with data
communication, or a power failure), the thermostat operates in the last valid room
operating mode (heating or cooling).
If a cable temperature sensor (QAH11.1 + ARG86.3) is connected to X1/X2, and
P38 or P40 = 2, the water temperature acquired by the changeover sensor
changes over from heating to cooling mode, or vice versa. When the water
temperature is above 28 °C (P37), the thermostat changes over to heating mode,
and to cooling mode when below 16 °C (P36).
If the water temperature is between the two changeover points immediately after
power-up, the thermostat starts in the previously active mode.
The water temperature is acquired at 30-second intervals and the operating state is
updated accordingly.
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:
3076Z03
X2
M
T
X2
M
QAH11.1
Contact open à heating mode
Contact closed à cooling mode
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 3.9.
By using an external switch for changeover, the operating action (P39 or P41)
cannot be modified.
· Contact open à heating mode
· Contact closed à cooling mode
Heating/cooling
Heating/cooling
changeover
Automatic
heating/cooling
changeover using
Changeover switch
Notes:
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