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Siemens
RXB (KNX) application library
FNC Description of functions for FC-10, FC-11, FC-12
CM110385en_05
Building Technologies
Control sequences
28 Feb 2009
•
It is not possible to ensure exact parallel running of more than one thermal valve
actuator. If several radiators are controlled by the same room controller, preference
should be given to motorized actuators.
If thermal actuators must nevertheless be controlled in parallel, third-party thermal
must be parameterized regardless of manufacture. This applies also if an external
power amplifier is used to drive the actuators.
•
Thermal actuators operate at a raised temperature. To ensure a fast response, the
actuators are continuously preheated to a slightly higher temperature (5% – 1 s ON /
19 s OFF). They therefore continue to receive pulses from the controller even when
closed.
Möhlenhoff actuators have been tested successfully in our HVAC laboratory.
Electromechanic third-party devices often have different runtimes for opening and
closing. For optimal control, the longer of the two running times must be parameterized.
When switching on the controller, after parameterization, after switching from test mode
to normal mode and for valve protection (unblocking, see page 91), the actuators are
synchronized:
•
Thermal heating and cooling valve actuators are controlled with "Open" for 5 minutes
(50% – 1 sec ON/ 1 sec OFF), then again for 5 minutes with "Close" (5% – 1 sec
ON/ 19 sec OFF).
•
Motorized actuators are first opened (110% of the runtime) and then closed (110%
of the runtime).
The sequence starts after synchronization.
The actuator type used must be defined at the engineering stage:
Select
Edit parameters, Sequences
:
Thermal valve actuators
Thermal third party
devices
Electromechanic third-
party devices
Synchronize
Parameterization
ETS3
Professional
