2-Pipe Fan Coil Unit With Radiator Or Floor Heating - Siemens RDG200KN Basic Documentation

Functions
4
Control sequences

4.7.5 2-pipe fan coil unit with radiator or floor heating

Heating or cooling with
radiator or floor heating
Radiator, active in cooling
mode
Radiator in heating mode
Floor heating
On/Off control
62 | 150
In 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 (P001 = 1).
In cooling mode, the valve receives an Open command if the acquired temperature
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
temperature is below the setpoint. The fan coil unit is used as an additional heat
source when the heating 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.
"Floor heating limitation (P252)" function, see Monitoring and limitation functions
[➙ 49].
The diagrams below show the control sequence for On/Off control.
Heating mode
T[°C] Room temperature
w Room temperature setpoint
YHC Control command "Valve" or
"Compressor"
YR Control command "Radiator"
Cooling mode
SDH Switching differential "Heating"
(P051)
SDC Switching differential "Cooling"
(P053)
SDR Switching differential "Radiator"
(P054)
X Dead zone (P055)
dz
w Setpoint differential (P056)
D
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