Siemens RDG400 - Manual (Page 20)

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Siemens RDG100…/RDG110…/RDG140.../RDG160… Basic Documentation CE1P3182en
Building Technologies Functions 28 May 2009
4.7.5 Single duct with electrical heater
In single duct applications with electrical heater, the thermostat controls a valve
plus an auxiliary electrical heater. Parameter P01 is not available.
The output signal for the air flow can be limited to a minimum and maximum value
if required (see section 4.6 "additional features").
The air flow starts to rise when the acquired room temperature is above "setpoint"
+ "dead zone".
The electrical heater receives an ON command when the acquired room
temperature drops below “setpoint” – “dead zone” (= “setpoint for electrical
heater”).
Remote enabling/disabling of the electrical heater is possible via input X1, X2, or
D1 for overheat protection, tariff regulations, energy saving etc.
Input X1, X2, or D1 must be commissioned accordingly (parameter P38, P40, P42).
See section 4.9 “Multifunctional input”.
In case of insufficient air flow, the thermostat cannot protect the electrical heater
against overtemperature. That is why the electrical heater must feature a separate
safety device (thermal cutout).
ON/OFF electrical heater
Modulating electrical heater
Y
YE
TR [°C]
dz
ma
x
mi
n
Y
0%
100%
TR [°C]
XpC
YV
C
Vmin
Vmax
ON
OFF
W
SDH
Y
0%
100%
YE
TR [°C]
XpH
W
dz
ma
x
mi
n
Y
0%
100%
TR [°C]
XpC
YV
C
Vmin
Vmax
Y Output signal
TR Room temperature
W Effective setpoint Comfort
H Heating sequence
C Cooling sequence
YV Volume flow rate
YE Electrical heater
XpH Proportional band heating
XpC Proportional band cooling
Vmin Minimum volume output
Vmax Maximum volume output
Note: The diagrams show the PI controller's proportional part only.
Setting the sequence and the control outputs
Refer to sections 4.5 (applications), 4.7.1 (sequences) and 4.7.3 (outputs).
Single duct with electrical
heater
Electrical heating,
active in cooling mode
Digital input “Enable
electrical heater”
Caution
Sequences