Technical data

3.6.3 2-pipe fan coil unit
On 2-pipe applications, the thermostat controls a valve in heating / cooling mode
with changeover (automatically or manually), heating only, or cooling only. Cooling
only is factory-set (P01 = 1).
On/Off control
The diagrams below show the control sequence for 2-position control.
Heating mode Cooling mode
½ SDH
1
0
½ SDH
w
Y
3191D01
T[°C]
YHC
Y
½ SDC
1
0
½ SDC
w
3191D02
T[°C]
YHC
T[°C] Room temperature
SDH Switching differential "Heating" (P30)
w Room temperature setpoint
SDC Switching differential "Cooling" (P31)
YHC Control command "Valve"
Modulating control: 3-position, PWM or DC 0…10V
The diagrams below show the control sequence for modulating PI control.
Heating mode Cooling mode
XpH
100
0
w
Y [%]
3191D03
T[°C]
YHC
XpC
Y [%]
100
0
w
3191D04
T[°C]
YHC
T[°C] Room temperature
XpH Proportional band "Heating" (P30)
w Room temperature setpoint
XpC Proportional band "Cooling" (P31)
YHC Control command "Valve"
The diagrams only show the PI thermostat’s proportional part.
Setting the sequence and the control outputs
Refer to sections 3.4 "Applications", 3.6.1 "Sequences", and 3.7 "Outputs".
Control sequence
On/Off output
Control sequence
modulating output
Note:
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Siemens RDG100KN, RDG160KN Basic documentation CE1P3191en
Building Technologies Functions 2014-05-23