2-Pipe Fan Coil Unit - Siemens DF301 Basic Documentation

ON/OFF control
Control sequence
ON/OFF output
Modulating control: 3-position
Control sequence
modulating output
Notes:
Setting the sequence and the control outputs
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Siemens...........................RDF301, RDF301.50..., RDF600KN, RDF600KN/VB, RDF600KN/S
Smart Infrastructure
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).
The diagrams below show the control sequence for 2-position control.
Heating mode
Y
Y1
1
w
T[°C]
0
½ SDH ½ SDH
T[°C] Room temperature
w Room temperature setpoint
Y1 Control command "Valve" or "Compressor"
The diagrams below show the control sequence for modulating PI control.
Heating mode
Y [%]
Y1
100
T[°C]
0
w
XpH
T[°C] Room temperature
w Room temperature setpoint
Y1 Control command "Valve"
· The diagrams only show the PI thermostat's proportional part.
· For the fan sequence see section 3.8.
Refer to section 3.4, section 3.6.1 and section 3.7.
Cooling mode
Y
Y1
1
w
T[°C]
0
½ SDC
½ SDC
SDH Switching differential "Heating" (P30)
SDC Switching differential "Cooling" (P31)
Cooling mode
Y [%]
Y1
100
0
w
XpC
XpH Proportional band "Heating" (P30)
XpC Proportional band "Cooling" (P31)
Basic Documentation
T[°C]
CE1P3171en
2020-02-21