Hello,
I haven’t found any box in Wago library Building HVAC able to optimize the ON-OFF time of a scheduler.
preheating and prestoping time: function of temperature room sensor , outside temperature sensor
Does-it exists ?
There is FbStartStopOptimalization. You can connect “iTimeBeforeOperation” from Scheduler function block. Here is the description:
Function
Function block calculates the optimal start and stop times of a heating installation.
Graphical Illustration
Function description
The FbStartStopOptimization function block calculates the optimal start and stop times of a heating installation.
The start time optimization aims to reach the required temperature at the beginning of the service period by starting up the heating on time. The stop time optimization switches the heating off before the end of service. In this process, the temperature may not be/fall below the defined specified temperature.
The optimization function can be deactivated by setting the xEnable input to FALSE signal. In this case, the xSwitchOn is linked directly to the xHeating output.
The time remaining until the service period iTimeBeforeOperation begins, or the remaining time up to the end of the service period, is determined by a FbScheduler function block.
Example
Start Time Optimization:
If the beginning of the normal start time has not been reached yet, the function block calculates the optimum start time according to the characteristic curve shown below. The characteristic curve gives the starting time per degrees Kelvin of deviation between the rReferenceValue reference and the actual value rActualValue. The dependency on the current outside temperature rOutsideTemperature is also taken into account.
- Example: navigation of level 3.
tStartLowTemperature = t#50m min/K tStartHighTemperature = t#10m min/K rOutsideTemperature = 0°C rActualValue = 18°C rReferenceValue = 20°C
For example, a start time of 30 min. is yielded from the characteristic curve at an outside temperature of 0°C.
By starting up the heating installation on time, the required reference temperature can be reached at the beginning of the service period. If the remaining time until the service period starts is smaller than the calculated start time, the xHeating and xOptimization outputs are switched to TRUE.
The xOptimization output signal is reset to FALSE when the required reference temperature, minus the .rVariation tolerance, is reached, or when the normal service period begins. This shows that the start time optimization is finished.
Ideally, the reference temperature is reached when the service period begins. If the room temperature is reached too early or too late, the characteristic curve can be adjusted automatically by shifting the grid points. This ensures that the thermal characteristics of the building are identified by the function block.
Automatic correction of the grid points will not be performed if the installation is switched off for more than 20 hours (see Holiday Effect).
Public Holiday Offset:
If the installation is switched off for more than 20 hours (e.g. on weekends or public holidays), a percentage offset is added to the calculated start time as a longer heat-up phase is required.
The percentage offset is calculated from a characteristic curve. The maximum value for the offset is reached after the heating installation has been switched off for 48 hours.
Stop Time Optimization:
The stop time optimization aims to save energy by switching off the heating installation before the service period is finished. In this case, the room temperature must not fall beyond a defined value during the period of use. The limit for the room temperature at the end of the service period is yielded from the reference value, minus the tolerance value (rReferenceValue - .rVariation).
The stop time is calculated from the characteristic curve shown below, which describes the relation between the outside temperature and the stop time. The characteristic curve indicates the stop time per Kelvin of deviation between the current room temperature and the room temperature limit at the end of the service period.
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Thank you Damian, it’s what I need , with good explication, just several variables and an example