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Zigbee devices Thermostats and radiator valves

Beca BHT-209-GCZB

Battery Zigbee thermostat with dry contact for boiler control. Works with Zigbee2MQTT with no vendor hub or cloud: it pairs with a Zigbee stick and shows up in Home Assistant.

Vendor
Beca
Model
BHT-209-GCZB
Type
Thermostats and radiator valves
Power
mains: usually a router that extends the mesh
Firmware updates (OTA)
no

Find it in shops: AliExpress

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What it exposes

FeaturePropertyValuesControl
On / offstate—settable
Child lockchild_lock—settable
Climatelocal_temperature, current_heating_setpoint, local_temperature_calibration, system_mode, running_stateroom temperature, heating setpoint, local_temperature_calibration, mode, running statesettable
Max temperature limitmax_temperature_limit°C · 35…45settable
Deadzone temperaturedeadzone_temperature°C · 1…5settable
Heating modeheating_mode—settable

MQTT: state and commands

Zigbee2MQTT publishes the device state to zigbee2mqtt/my_device (my_device is the name you give the device). An example message:

{
  "state": false,
  "child_lock": false,
  "local_temperature": 20.5,
  "current_heating_setpoint": 21,
  "system_mode": "heat",
  "max_temperature_limit": 40,
  "deadzone_temperature": 3,
  "heating_mode": false,
  "linkquality": 120
}

Send commands to zigbee2mqtt/my_device/set:

mosquitto_pub -t zigbee2mqtt/my_device/set -m '{"current_heating_setpoint":21.5}'
mosquitto_pub -t zigbee2mqtt/my_device/set -m '{"system_mode":"heat"}'
mosquitto_pub -t zigbee2mqtt/my_device/set -m '{"state":true}'
mosquitto_pub -t zigbee2mqtt/my_device/set -m '{"child_lock":true}'
mosquitto_pub -t zigbee2mqtt/my_device/set -m '{"heating_mode":true}'

Watch the topics live from the browser: MQTT client.

Home Assistant automation example

Zigbee2MQTT creates Home Assistant entities from the device name. If it is called my_device, an automation in automations.yaml can look like this:

- alias: "Cooler at night"
  mode: single
  triggers:
    - trigger: time
      at: "23:00:00"
  actions:
    - action: climate.set_temperature
      target:
        entity_id: climate.my_device
      data:
        temperature: 18

Check the YAML: YAML checker.

How to pair it

  1. In Zigbee2MQTT click Permit join.
  2. Put the device in pairing mode: usually a long press of the reset button (5–10 s) until the LED blinks; bulbs: switch the power off and on 5–6 times.
  3. Keep the device close to the coordinator or a router while pairing.
  4. Give it a clear name: MQTT topics and Home Assistant entities are built from it.

Exact procedure and model notes: the device page in the Zigbee2MQTT docs. No coordinator yet: coordinator picker.

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