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Siemens
RXB (KNX) Applications library
CLC and RAD description of functions for CC-02 CM110384en_03
Building Technologies
Control sequences
28 Feb 2009
8.2
Chilled ceiling (CLC01)
The chilled ceiling application has a continuous cooling sequence. The room controllers
operate with a PI algorithm optimized for thermal or motorized valve actuators. (For
simplicity, the diagram below only shows the P-control action.)
The control sequence comes into operation at the effective setpoints for cooling (see
page 67).
100
0
TR [°C]
Y [%]
SpC
YC
C
Y Output
signal
TR Room
temperature
SpC Effective
cooling
setpoint
C Cooling
sequence
YC Cooling
valve
8.2.1
Select actuator types for chilled ceiling
See section
, page 79 on selecting actuator types for radiators.
The following information differs from the radiator applications:
HandyTool
Parameter Short
name
Basic setting
*051
Actuat c’surf valve
STA71
Settings
STE71 1
SSA81 10
Motoric
bus
250
STA71 3
SSB81 11
El’mech
3
rd
party devices
252
STP71 4
SQS81 12
Thermal
3
rd
party devices
253
STA72E 5 SSC81 13 Motoric
3
rd
party devices
254
STP72E 6 SSP81 14
•
If thermal actuators are selected, Y3 / Y4 are always controlled in parallel to ensure
that several actuators can be connected at the same time.
•
Exact parallel operation of several thermal valve actuators is not guaranteed. If
several radiators are controlled by the same controller, motorized actuators are the
preferred device.
If nevertheless thermal actuators are controlled in parallel, "3rd Party Thermic" must
be parameterized regardless of make.
•
Thermal actuators work at higher temperatures. To ensure a fast reaction, the
actuators are slightly preheated continuously (5% – 1 sec ON / 19 sec OFF). Then
thus also receive pulses from the controller when closed.
Actuator type
Thermal valve actuators
Notes