The master actuator unit(s) is the brain of the HVAC system. It fulfills all of the functions of a slave actuator unit  and includes other capabilities, such as: ​

  • Collection of all sensors data from indoor sensor unit(s), outdoor sensor unit(s) and slave actuator unit(s)​
  • Additional weather information may be collected from the internet, if an IP gateway is implemented in the master actuator or separately (see IP Gateway for Automatic Home or Building HVAC System) ​
  • Calculation/Determination of the set points for each slave actuator unit, like flow direction (in/out), temperature, etc., using an algorithm or the latest embedded artificial intelligence (AI) technology​
  • Provision of the set points for each slave actuator and the master itself​
  • Local (graphical) GUI of the whole system, which may also be mirrored by a Bluetooth® or web interface​
  • Real-time clock (RTC) and its distribution to sensor/actuator units for different operation modes, depending on the day, time, holiday, etc.​


From a system perspective, the master and slave actuator can have the same hardware and software. In this case, the master is a role rather than a certain device and it would not represent a single-point-of-failure, as another slave actuator could take over the master role in case the original master fails. However, there must be only one master, per system, at a time.​

System Benefits​

  • The RX23W MCU enables Bluetooth 5 mesh communication​
  • The master actuator can (but does not need to) have an integrated gateway to the intranet/internet using a secure communication mechanism like HTTPS or MQTT, if not achieved externally (see IP Gateway for Automatic Home or Building HVAC System). For these cases, one or multiple of the following technologies are available:​
    •   Wi-Fi (based on IEEE 802.11), Thread or Zigbee (based on IEEE 802.15.4), Ethernet (based on IEEE 802.3), LTE-M/-NB (depending on geographical region and available providers), or LoRaWAN​

*Note: For the power supply, usually the mains will be needed for the fan/HVAC (e.g., 230Vac or 110Vac, or 24Vdc from the building control system). 

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eu079-block-diagram

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