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Siemens RDG100, RDG100T, RDG110, RDG140, RDG160 Basic Documentation CE1P3181en
Building Technologies Functions 28 May 2009
4.7.5 2-pipe fan coil unit with radiator or floor heating
On 2-pipe applications with radiator, the thermostat controls a valve in heating /
cooling mode with changeover, heating only, or cooling only plus a radiator valve.
Cooling only is factory-set (P01=1).
In cooling mode, the valve receives an OPEN command if the acquired tempera-
ture is above the setpoint.
The radiator receives an ON command if the acquired room temperature drops
below “setpoint” minus “dead zone” (= “setpoint for radiator”).
In heating mode, the radiator receives an OPEN command if the acquired tempera-
ture is below the setpoint. The fan coil unit is used as an additional heat source
when the heat energy controlled by the radiator is insufficient.
The fan coil unit receives an ON command if the temperature is below “setpoint”
minus “setpoint differential” (= setpoint for fan coil unit).
The radiator sequence can also be used for floor heating.
The "Floor heating limitation function" is described on page 17.
The diag
ram belo
w shows the control sequence for 2-position control.
Heating mode
(automatic changeover = heating or heating only)
Cooling mode
(man. /auto. changeover = cooling or cooling only)
Y
½ SDH
1
0
½ SDH
w
3181D120
T[°C]
YR
½ SDH
½ SDH
Y1
w
D
Y
½ SDC
1
0
½ SDC
w
3181D121
T[°C]
Y1
½ SDH
½ SDH
YR
x
dz
T[°C] Room temperature SDH Switching differential “Heating” (P30)
W Room temperature setpoint SDC Switching differential “Cooling” (P31)
Y1 Control command “Valve” or “Compressor” X
dz
Dead zone (P33)
YR Control command “Radiator” w
D
Setpoint differential (P34)
Heating or cooling with
radiator or floor heating
Radiator, active in
cooling mode
Radiator in heating mode
Floor heating
ON/OFF control
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