EN - How to set the ventilation temperature

EN - How to set the ventilation temperature

  
Question

How to set the ventilation temperature

 Answer 

The picture below shows the greenhouse climate settings.



You can select the first 3 settings like this:
​



Here you see the 3 selected settings in 1 picture:



The numbers in the picture explained:
  1. This is the graph of the heating temperature
  2. The first tab is the setting of the heating temperature
  3. This is the graph of the ventilation temperature at the lee side
  4. The second tab is the setting of the ventilation temperature at the lee side
  5. This is the graph of the ventilation temperature at the wind side
  6. The third tab is the setting of the ventilation temperature at the wind side
Most of the time the settings of the heating and ventilation temperatures are made like this.
A temperature difference between heating temperature and ventilation temperature lee side of for example 1 degree.
And a temperature difference between ventilation temperature lee side and ventilation temperature wind side of for example 1 degree.

Example



The minimum greenhouse temperature is controlled by the heating temperature.
The maximum greenhouse temperature is controlled by the ventilation temperature leeside, ventilation temperature windside and cooling temperature.
If the greenhouse temperature is higher than 22 °C then the leeside starts to open. With an automatic P-band of 5 °C the vents at the leeside will be opened 100% when the greenhouse temperature reaches 27 °C. In the meantime the windside is also opened, because the windside starts opening at 24 °C. With an automatic P-band of 7°C the vents will be opened 43% at that moment.
If the greenhouse temperature increase more, than the windside will open more and at 29 °C the cooling will switch on.


The temperature is controlled by the heating and the vents.

Heating control
When the greenhouse temperature is below the heating setpoint, then the heating is starting.
The pipe temperature for the heating is calculated very precisely.
This calculation is based on a pre-control.
This pre-control is looking to the outside conditions like sunlight, outside air temperature, wind and rain.
So when it is cold outside then the calculated pipe temperature will be higher. When it is sunny then the calculated pipe temperature will be lower etc.
Also the heating history is involved in this calculation, so the heating control knows exactly which pipe temperature is needed at which temperature difference.

Ventilation control
Like you see in the picture above the vents are opened via a P-band. So the higher the greenhouse temperature, the higher the vent position.
This is done very smoothly.
The automatic P-band is also based on a pre-control.
So when it is cold outside then the calculated P-band will be higher. When it is sunny then the calculated P-band will be lower etc.

Summary
So the heating control and the ventilation control are not ON/OFF controls, but very smoothly controls.



    • Related Articles

    • EN - iSii compact: How to set up the Ventilation control

         Question How to set up the Ventilation control?  Answer  The setpoints for ventilation can be found as follows:     The ventilation vents will be controlled in the following cases: Too high greenhouse temperature Too high relative humidity ...

    • EN - How to set the heating temperature

         Question How to set the heating temperature  Answer  The picture below shows the heating temperature. The numbers in the picture explained: This is the day temperature, 19 °C This is the night temperature 18 °C Most of the time the night ...

    • EN - iSii compact: How to connect Ventilation strategy ?

      Question How to connect Ventilation strategy in iSii compact? Answer Layout control block - v1.5.0 Control block Ventilation strategy contains 2 vent position calculators: 1 for lee and 1 for wind side Layout vent position calculators in Ventilation ...

    • EN - How to close the vents before opening the screens to avoid cold fall

          Question How to close the vents before opening the screens to avoid cold fall?  Answer  Example 1 The screen is closed during the night as energy screen. The ventilation temperature can be increased as soon as the curtain is opening. This is done ...

    • EN - How to do maintenance on a pH sensor

             Question How to do maintenance on a pH sensor?  Answer  As you can see in the table below, you can clean the sensor with clean water. Watch the video below how to calibrate an pH sensor: The calibration procedure in steps: ​In this video we ...