This article will give you a more detailed description of how this function works and behaves when a temperature is set.
All Products that support the external temperature sensor function.
Intesis AC Interface
External Temperature Sensor
IN THIS ARTICLE
For the sake of simplicity, KNX is used as a reference in this article. However, this is also applicable to the Modbus variant.
The base of the function is the following calculation.
“AC Setp. Temp.” = “Ambient ref. Temp.” - (“KNX Amb. Temp.” - “KNX Setp Temp.”)
- AC Setp. Temp.: AC indoor unit setpoint temperature (Temp. set on the AC)
- Ambient Ref. Temp.: AC indoor unit return temperature (Temp. measured by the AC)
- KNX Amb. Temp.: Ambient temperature provided from KNX (Temp. measured by KNX)
- KNX Setp. Temp: Setpoint temperature provided from KNX (Temp. set from KNX)
As an example, consider the following situation:
User wants: 19ºC (KNX Setp. Temp.)
User sensor (a KNX sensor) reads: 21ºC (KNX Amb Temp.)
Ambient temp. read by the AC is: 24ºC (Ambient Ref. Temp)
In this example, the final setpoint temperature that the Gateway will send out to the indoor unit (“Setp.
Temp.”) will become 22ºC = 24ºC – (21ºC - 19ºC). This is the setpoint that will be sent to the AC unit.
This formula will be applied as soon as the Control_ Setpoint Temperature and Control_ Ambient
Temperature objects are written at least once from the KNX installation. After that, they are kept always
Note: This formula will always drive the AC indoor unit demand in the right direction, regardless of
the operation mode (Heat, Cool, or Auto).
On the following page, you can see a diagram that shows the behavior of the target temperature of the
AC unit in relation to certain time-based (time 1,2,3,...) temperature values.
As described above the User wants a Temperature of 19°C in his Room. The KNX Sensor Measures 21°C
and the AC Measures 24°C
Time 1: Start (AC Setp. Temp 22°C)
Time 2: AC Amb. Temp. decrease to 23 °C (AC Setp. Temp. decrease to 21°C)
Time 3: AC Amb. Temp. decrease to 22 °C (AC Setp. Temp. decrease to20°C)
Time 6: KNX Amb. Temp. decrease to 20 °C (AC Setp. Temp. increase to 19°C)
Time 8: Temp. reached (unstable)
Time 9: KNX Amp. Temp. below 19 °C (AC Setp. Temp. increase to 20°C)
Time 10: Temp. reached (unstable)
Time 11: Temp. reached (stable)