Page 45 - Advanced Course

KNX ADVANCED COURSE

Control options according to actuators
Table 6

Control option Comment
Direct heating circuit Heat requirement can only be regulated by switching
the secondary heating pump on/off

Mixed circuit Heat requirement can only be regulated by
opening/closing the mixing valve and via the boiler
circuit when there is a lack of heat

Figure 18: Heating curve for control via the spread
Example: Control via the spread (flow/return sensor)
When the installation has the correct layout, the setpoint room temperature is achieved if
a return temperature of approx. 42°C is set e.g. at an external temperature of 0°C and a
flow temperature of approx. 58°C. A deviation in the return temperature leads to an
adjustment of the setpoint flow temperature.

The ideal type of control is achieved if the heat requirement of a room influences the
operation of the heat source.
In a rented or owner-occupied flat, the user can achieve an energy saving using KNX
individual room control without intervening in the heating system. No real problems arise.
This is particularly suitable for installations with a central heat source.
It is advisable in detached houses to combine the KNX individual room control with the
heating circuit and boiler control. In this case, only the heat that is needed is generated. It
is then necessary to use boiler and mixed circuit controllers with KNX capability (heating
manufacturers: Viessmann, Buderus, Stiebel-Eltron).

Home and Building Management Systems KNX Association
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