Art. No. SC 1000 KNX
- "Change-over between heating and cooling" parameter in the "Room temperature control
-> Controller general -> Setpoints" parameter branch set to "Via object".
In this case, the operating mode is controlled via the object "Heating/cooling change-over",
irrespective of the deadband. This type of change-over can, for example, become
necessary if both heating and cooling should be carried out through a one-pipe system
(heating and cooling system). For this, the temperature of the medium in the single-pipe
system must be changed via the system control. Afterwards the heating/cooling operating
mode is set via the object (often the single-pipe system uses cold water for cooling during
the summer, hot water for heating during the winter).
The "Heating/cooling change-over" object has the following polarities: "1": heating; "0"
cooling. After a reset, the object value will be "0", and the "Heating/cooling operating mode
change-over after reset" set in the ETS will be activated. You can use the "Heating/cooling
operating mode after reset" parameter to set which mode you want to activate after a reset.
For the "Heating" or "Cooling" settings, the controller will activate the configured heating/
cooling operating mode immediately after the initialisation phase. In case of
parameterisation "Operating mode before reset" the operating mode which was selected
before the reset will be activated.
If a change-over is made through the object the operating mode will first be changed into
the one specified to be activated after a reset. A change-over to the other operating mode
will only take place after the device receives an object update, if necessary.
Notes on the setting "Operating mode before reset": frequent changing of the operating
mode (e. g. several times a day) during running operation can adversely affect the life of
the device as the read-only memory (EEPROM) used has been designed for less frequent
write access events only.
It is not possible to heat and cool at the same time (command value > "0"). Only with PWM is it
possible that a short-time 'command value overlapping' could occur during the transition
between heating and cooling, due to the matching of the command value at the end of a time
cycle. However, such overlapping will be corrected at the end of a PWM time cycle.
Heating/cooling message
Depending on the set operating mode, separate objects can be used to signal whether the
controller for the first control circuit is currently demanding heating or cooling energy and is thus
actively heating or cooling. As long as the heating command value is > "0", a "1" telegram will
be transmitted through the "Heating" signal object. The signal telegram is only reset when the
command value is "0" ("0" telegram is transmitted). The same applies to the signal object for
cooling.
i It should be noted that with a 2-point feedback control the message objects for heating and
cooling will already become active as soon as the temperature falls short of the
temperature setpoint of the active operating mode in case of heating or exceeds the
temperature setpoint in case of cooling. In this case, the configured hysteresis is not taken
into account.
The signal objects can be enabled by the "Heating message" or "Cooling message" parameters
in the "Room temperature control -> Command value and status output" parameter branch. The
control algorithm controls the signal objects. Please note that the command value is
recalculated every 30 s, followed by an updating of the signal objects.
Page 169 of 347
Software "Smart Control 501511"
Functional description
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