OpenTherm Thermostat firmware v1.10
  • 2/25/2024

OpenTherm Thermostat firmware v1.10

A new v1.10 is ready to update.

New features
  • MQTT state extended
    1. BLE sensor data
    2. Return water temperature
  • MQTT TLS Support
  • Unique MQTT Topics
  • Maximum relative modulation level set via MQTT
  • Display brightness, dim and off settings (for v2)

  • MQTT sensor 'last seen' invalid calculation
  • BLE sensor packet loss ratio calculation (invalid after sensor type change)
  • Reading OT float type for negative values (for external temperature)

MQTT thermostat state message was extended with a following properties:

chMin               // CH minimum temperature, °C
chMax               // CH maximum temperature, °C
bleBatt             // BLE sensor battery, mV
bleBattLevel        // BLE sensor battery, %
bleHumidity         // relative humidity, %
blePacketLossRatio  // packet loss ratio, %
bleRssi             // BLE signal strength, dBi
bleLastSeen         // time since last BLE packet was received, seconds

An Unique MQTT Topics enables possibility of using a multiple thermostats within the same MQTT Broker by changing the topics to use device's MAC address, i.e.

A BLE loss ratio and/or BLE RSSI indicators can be used to estimate a connection quality between the thermostat and a sensor. Poor signal quality might result in either frequent boiler start/stops or inefficient heating if the option 'Heat on sensor failure' is used.
In case of a large distance between sensor and thermostat you might consider either switching to an OpenTherm Thermostat 2 (it is ESP32-S3 based and has better BLE sensitivity) or using a BLE Repeater (i.e. simple ESP32-based repeater, can be also flashed to S3 variant).