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Siemens
RDG100.., RDG110.., RDG160T.. Basic Documentation
CE1P3181en
Building Technologies
Functions
2015-07-29
4.7.7 4-pipe fan coil unit with electric heater (RDG100..)
On 4-pipe applications with electric heater, the thermostat controls 2 valves in heating
and cooling mode by manual selection, heating and cooling mode with automatic
changeover, heating only, or cooling only plus an electric heater.
Heating and cooling is factory-set (P01=4).
The electric heater is used as an additional heat source when the heating energy
controlled by the valve is insufficient.
The electric heater receives an
ON
command when the temperature is below
"setpoint" minus "1/2 dead zone" minus "setpoint differential" (= "setpoint for electric
heater").
Remote enabling/disabling of the electric heater is possible via input X1, X2, or D1 for
tariff regulations, energy saving, etc.
Input X1, X2, or D1 must be commissioned accordingly (parameters P38, P40, P42).
See section 4.10 for details.
An electric heater must always be protected by a safety thermostat!
The heating or cooling output can be released via operating mode button if parameter
P01 is set to manual (P01=2).
See section 4.7.6 for details.
The diagrams below show the control sequence for 2-position control.
Heating mode with
manual
selection (P01=2)
Cooling mode with
manual
selection P01=2)
Heating and cooling mode (P01=4)
T[°C] Room temperature
w
Room temperature setpoint
YE Control command "Electric heater"
YH Control command "Valve" or "Comp." (H)
YC Control command "Valve" or "Comp." (C)
SDH Switching differential "Heating" (P30)
SDC Switching differential "Cooling" (P31)
X
dz
Dead zone (P33)
w
D
Setpoint differential (P34)
Heating and cooling with
auxiliary heater
Electric heating in
heating mode
Digital input "Enable
electric heater"
Caution
4-pipe application with
manual changeover
"Main and secondary"
application
On/Off control