Single-Duct Applications With Heating/Cooling Coil - Siemens KNX RDG400KN Basic Documentation

Water coil valve in
cooling mode
Water coil valve in
heating mode
Control sequence
Siemens
Smart Infrastructure
3.6.8

Single-duct applications with heating/cooling coil

On single-duct applications with heating/cooling coil, the thermostat controls an
actuator (air damper, VAV system, etc.) plus a heating/cooling water coil.
The output signal for the air flow can be limited to a minimum and maximum value
if required (see section 3.4.1).
The thermostat controls the reheating/cooling water valve either in heating/cooling
mode with changeover (automatically or manually), heating only, or cooling only.
Cooling only is factory-set (P01 = 01).
The air flow starts to rise depending on the acquired room temperature, the current
supply air temperature (if available) and the setpoint.
If the room temperature is above the setpoint for cooling (w), the valve receives an
Open command and the air flow signal starts to rise to maintain the room
temperature setpoint.
If the room temperature drops below the setpoint for heating (w), the valve receives
an Open command.
The diagrams below show the control sequence for modulating PI control in
Comfort mode.
2-position heating/cooling coil
Y Changeover air
XpH
H
10.3 mm
100%
Vmax
Vmin
0%
Changeover water
Y
SDH
H
7.0 mm
ON
YHC
w
OFF
dz
20.1 mm
Y Output signal
TR Room temperature
w Comfort setpoint when heating sequence active
(w) Comfort setpoint when cooling sequence active
H Heating sequence
C Cooling sequence
YV Volume flow rate
RDG400KN,RDG405KN Basic documentation
Modulating heating/cooling coil
XpC
C
5.2 mm
100%
Vmax
YV
Vmin
TR [°C]
SDC
C
4.9 mm
100%
YHC
(w)
TR [°C]
XpH
XpC
Vmin
Vmax Maximum volume output
SDH
Changeover air
Y
XpH
H
10.3 mm
0%
Changeover water
Y
XpH
H
10.0 mm
YHC
(w)
w
0%
dz
19.6 mm
Proportional band heating
Proportional band cooling
Minimum volume output
Switching differential heating
XpC
C
5.2 mm
YV
TR [°C]
XpC
C
4.9 mm
YHC
TR [°C]
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CE1P3192en
2019-04-12