User Manual

Functions
Control sequences
4
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4.7.3 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 (factory
setting, P001 = 1).
The diagrams below show the control sequence for On/Off control.
Heating mode Cooling mode
T[°C] Room temperature
SDH Switching differential "Heating"
(P051)
w Room temperature setpoint
SDC Switching differential "Cooling"
(P053)
YHC Control command "Valve"
The diagrams below show the control sequence for modulating PI control.
Heating mode Cooling mode
T[°C] Room temperature
XpH Proportional band "Heating"
(P050)
w Room temperature setpoint
XpC Proportional band "Cooling"
(P052)
YHC Control command "Valve"
The diagrams only show the PI thermostat’s proportional part.
For setting sequence and control outputs, see Applications overview [➙ 36],
Sequence overview (setting via P001) [➙ 54] and Control outputs [➙ 75].
Parameter P256 (RDG260KN) sets the heating flow limitation when using a PICV.
See Additional functions [➙ 41].
On/Off control
Control sequence
On/Off control output
Modulating control:
3-position, PWM or
DC 0…10 V
Control sequence
modulating output
Note
Note