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Siemens
RDF300… / RDF340... / RDF400… / RDF600… Basic Documentation
CE1P3076.en
Smart Infrastructure
2020-02-21
Use with one 1-stage compressor for heating and cooling, or cooling only, or
heating only.
Thanks to a flexible fan control, the RDF3xx / RDF4xx can also be used in
universal applications, e.g. fan coil-based cooling and floor heating, or chilled
ceiling and electrical heater etc. See also section 4.8 “Fan control”.
4.5
Additional features
The water temperature acquired by the changeover sensor (QAH11.1 + ARG86.3)
is used to change over from heating to cooling mode and vice-versa. When the
water temperature is above 28 °C (parameter P37), the controller 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 controller starts in previous 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:
Contact open
à
heating mode
Contact closed
à
cooling mode
The sensor or switch can be connected to the input terminal of X2 (factory setting)
or X1 depending on the commissioning of inputs X1 and X2. See also section 4.9
“Multifunctional input”.
The controller 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 need to be commissioned accordingly. See section 4.9 “Multi-
functional input”.
The changeover sensor is tasked with initiating changeover from heating to cooling
mode based on the acquired water temperature. We recommend activating the
purge function (parameter P50) with 2-port valves. This function ensures correct
acquisition of the medium temperature even if the 2-port valve is closed for an
extended period of time. The valve is then opened for 1 to 5 minutes (adjustable) at
2-hour intervals during off-hours.
The purge function (parameter P50) must be disabled if the controller is to be used
in compressor-based applications.
Compressor-based
application
Universal applications
Automatic H/C
changeover
Remote heating/
cooling changeover
External / return air
temperature sensor
Purge function
Caution
