Siemens RDG400 manual Single duct with electrical heater, Sequences, Modulating electrical heater

	4.7.5	Single duct with electrical heater
Single duct with electrical	In single duct applications with electrical heater, the thermostat controls a valve
heater	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").
Electrical heating,	The air flow starts to rise when the acquired room temperature is above "setpoint"
active in cooling mode	+ "dead zone".
	The electrical heater receives an ON command when the acquired room
	temperature drops below “setpoint” – “dead zone” (= “setpoint for electrical
	heater”).
Digital input “Enable	Remote enabling/disabling of the electrical heater is possible via input X1, X2, or
electrical heater”	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”.
Caution	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).

Sequences ON/OFF electrical heater

Y
XpC	C
100%
Vmax	max
YV
Vmin
min
0%

TR [°C]

Y

SDH

ON

YE

Modulating electrical heater

Y	XpC
100%		C
Vmax		max
Vmin	YV
	min
0%	TR [°C]

Y

XpH

100%

YE

OFF

W

dz TR [°C]

0%	W
	dz	TR [°C]

Y	Output signal
TR	Room temperature

WEffective 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).

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Siemens	RDG100…/RDG110…/RDG140.../RDG160… Basic Documentation	CE1P3182en
Building Technologies	Functions	28 May 2009