Siemens RDB160BN - 2-Pipe Fan Coil Unit with Electric Heater

Applications
Control sequences
4
16
| 52 A6V11917618_en--_b
Modulating control
Control sequence modulating output, PWM, DC 0…10 V or 3-position:
The diagrams below show the control sequence for modulating PI control.
Heating and cooling mode
Cooling mode
T[°C]
Room temperature
V1
Control command 'Valve'
W
Room temperature setpoint
Xp
Proportional band (P08)
NOTICE
The diagrams only show the PI proportional part of the thermostat.
For detailed information about setting the sequence and the control outputs
refer to chapters 'Applications [➙ 11]', 'Setpoint and sequences [➙ 18]' and
'Control outputs [➙ 20]'.
4.3.3 2-pipe fan coil unit with electric heater
Heating or cooling with auxiliary heater
In 2-pipe applications with an electric heater, the thermostat controls a valve in
heating or cooling mode based on the changeover: Heating only or cooling only
with electric heater. Parameter P01 is set to 4.
The electric heater can only be controlled with output DO5 (Triac) with an
On/Off control logic. An external relay is used if the Triac power rating is
insufficient.
Electric heating, active in cooling mode
In cooling mode, the valve receives an 'Open' command if the measured
temperature is above the setpoint temperature.
The electric heater receives an 'On' command if the measured room
temperature drops below the setpoint temperature minus dead zone
(parameter P05) and hysteresis (parameter P10).
Electric heating in heating mode
In heating mode, the valve receives an 'Open' command if the measured
temperature is below the setpoint temperature. The electric heater is used as
an additional heating source when the heating energy controlled by the valve is
insufficient.
The electric heater receives an 'On' command if the temperature is below the
setpoint temperature minus hysteresis (parameter P10) and the first heating
sequence has reached 100 %.
T [°C]
V1
100
0
Y [%]
X
P
w
T [°C]
V1
100
0
Y [%]
X
P
w