The HeatingCurve calculates the flow temperature setpoint using a heating curve depending on the room temperature setpoint and the outside air temperature. The output is used as a setpoint for a flow temperature (mixed water temperature) control loop.
HeatingCurve calculates an outside air-compensated flow temperature setpoint, depending on a room temperature setpoint connected to a time schedule, using a heating curve. If a room temperature sensor is connected, the controller can adapt this heating curve automatically. This setpoint is the input of a PID controller, which compares the measured flow with the flow temperature setpoint.
The controller uses parameters to perform several tasks to ensure an economic heating. Apart from the basic functions it performs (to control the desired temperature according to a time schedule), the controller also ensures that certain temperatures are maintained to protect the system or building. Default settings for each parameter are based on years of experience to ensure this safe operation. Adjustments are only necessary in very special cases.
The weather-compensated controller requires a heating curve for each heating circuit to determine the correct flow temperature setpoint according to outside air temperature. The heating curve graph indicates the relationship between outside air temperature and associated flow temperature.
For radiator heating systems, a heating curve slope 1.6 and curvature 1.33 is the default setting. The higher the curvature value, the more pronounced the curvature. Recommended curvature values are:
It is important to set the curvature value appropriately for under-floor heating systems to avoid damages caused by excessive flow temperatures. A safety thermostat is recommended to switch off the heating pump if the flow temperatures are too high.
For radiator heating systems, the maximum thermostat is not important since high flow temperatures cannot cause any damage.
The controller can use filtered values of the room, outside air, and flow temperatures to automatically and gradually adjust the heating curve.
The controller measures the room temperature throughout the day. Starting with the third day, the controller starts correcting the heating curve by adapting it to average room temperature. If the curvature value is too high (for example, 1.6), the flow temperature during the first few days may also be too high. Adaptation over a relatively long period of time results in a well-adjusted heating curve.
If you use a sample room to test the adaptation function, make sure there is NO thermostatic radiator valve (where the room sensor is installed). The radiator in the sample room must always be open otherwise automatic adaptation does not function or the results are interpreted incorrectly. Too frequent airing and open windows in the sample room also have a negative effect on the adaptation procedure.
If no room sensor is installed, the controller functions as a weather-compensated controller with the default heating curve setting.
Fig. 198. Wire-sheet Icon
Fig. 199. Property Sheet
Fig. 200. Slot Sheet
Table 123. Inputs
Inputs |
Type |
Functional description |
In RoomTempSp |
numeric |
Room temperature setpoint |
In FiltOATemp |
numeric |
Filtered outside air temperature |
In RoomTemp |
numeric |
Room temperature The room temperature setpoint input must be connected to an analog point assigned to a time schedule. |
In SysSupplyTemp |
numeric |
System supply temperature from the heat generators |
In PumpStatus |
boolean |
Heating pump status – can be set to true or false in the property sheet. If you want to connect it to a real pump status input, you can check the “Summary” flag in the Slot Sheet |
In Enabled |
boolean |
If the input “In Enabled” is set to false disabled in the slot sheet, the output “Out” will be disabled and is set to the value “0”. |
The inputs “in RoomTemp”, “In SysSupplyTemp” and “In PumpStatus” are only required only of the adaptation is enabled.
Table 124. Outputs
Outputs |
Type |
Functional description |
Out FlowTempSp |
numeric |
Flow temperature/ mixed water temperature setpoint |
Table 125. Parameter List
Description |
Value Range |
Default Value |
Unit |
Adaptation mode |
Enabled Disabled Restart |
Disabled |
- |
Heating curve slope limit |
0.4 to 4.5 |
4,5 |
- |
Heating curve curvature |
0…2 |
1,33 |
- |
Heating curve slope |
0.4 to 4.5 |
1,6 |
- |