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Siemens RDG100KN Basic documentation CE1P3191en
Building Technologies Functions 22 Jun 2010
3.6.8 2-stage heating or cooling
On 2-stage applications, the thermostat controls 2 valves or compressors in
heating or cooling mode or changeover (automatically or manually).
“Cooling only" is factory-set (P01 = 1).
In heating mode, the 1st stage is activated if the acquired temperature is below the
setpoint.
The 2nd stage is activated if the acquired room temperature drops below “setpoint”
minus “setpoint differential”.
In cooling mode, the 1st stage is activated if the acquired temperature is above the
setpoint.
The 2nd stage is activated if the acquired room temperature rises above “setpoint”
plus “setpoint differential”.
The diagrams below show the control sequence for 2-position control.
Heating mode (P01 = 0) Cooling mode P01 = 1)
Y
TR [°C]
1
0
w
SDH
SDH
w
D
Y2
Y1
3181D15a
Y
TR [°C]
SDCSDC
Y1
Y2
3181D16a
w
w
D
1
0
Changeover (P01 = 2 or P01 = 3)
T[°C] Room temperature
w Room temperature setpoint
Y1 Control command “Stage 1"
Y2 Control command “Stage 2”
SDH Switching differential “Heating” (P30)
SDC Switching differential “Cooling” (P31)
X
dz
Dead zone (P33)
Y
TR [°C]
SDH
SDH
SDC
SDC
Changeover
Y2
Y1
Y2
3181D17a
w
w
D
w
D
1
0
w
D
Setpoint differential (P34)
2-stage heating
or cooling
Heating mode
Cooling mode
ON/OFF control