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Siemens
RDG100.., RDG110.., RDG160T.. Basic Documentation
CE1P3181en
Building Technologies
Functions
2015-07-29
Setting the sequence and the control outputs
Refer to section 4.5, 4.7.1 and 4.7.2.
4.7.6 4-pipe fan coil unit
On 4-pipe applications, the thermostat controls 2 valves in heating and cooling mode,
heating/cooling mode by manual selection, or heating and cooling mode with
changeover. Heating and cooling mode (P01=4) is factory-set.
The heating or cooling output can be released via operating mode button if parameter
P01 is set to manual (P01=2).
If parameter P01 is set to changeover (P01=3), the heating and cooling output is
swapped according to the changeover sensor input status (see automatic heating and
cooling changeover sensor, section 4.6). This mode is used for the so-called "Main
and secondary" application. This is a 4-pipe fan coil unit system with different capacity
of the 2 coils. The water circuit is changed to optimize the energy exchange
depending on the season (summer/winter):
– Winter: Large coil (V1) for heating, small coil (V2) for cooling
– Summer: Large coil (V1) for cooling, small coil (V2) for heating
T
B1
V2
V1
M1
3
18
1
D
1
12
T
B2
Note:
This example shows
On/Off control;
for modulating con-
trol, connect the
appropriate output
terminals.
The factory setting for the heating and cooling changeover sensor (B2 in the above
diagram) is input X2 (P40 = 2)
The thermostat assumes winter operation when B2 > P37
(factory setting 28 °C (82 °F))
The thermostat assumes summer operation when B2 < P36
(factory setting 16 °C (61 °F))
Heating and cooling
4-pipe application with
manual changeover
"Main and secondary"
application (4-pipe with
changeover)
Notes