ZWT198 Temperature into HAS via MQTT

Introduction

The ZWT198 thermostat does not directly transmit its temperature to Home Assistant. To access this information, we need to retrieve it through the MQTT protocol. This guide explains how to integrate this data into Home Assistant, enabling us to monitor and utilize our thermostat's temperature within Home Assistant.

Integration Steps

Verify MQTT Messages with MQTT Explorer

To confirm that the thermostat is publishing temperature data to the MQTT broker, we use MQTT Explorer. Connect to your broker and navigate to the topic corresponding to your thermostat, for example: zigbee2mqtt/Zigbee Thermostat Living Room ZWT198. Ensure that the message contains the key local_temperature with a numeric value.

Image of the MQTT Explorer interface displaying the relevant topic and the message containing the local_temperature key.

Add MQTT Sensor Configuration in Home Assistant

To have Home Assistant create a sensor that retrieves the temperature from the MQTT message published by the thermostat, access the configuration.yaml file and add the following configuration:

mqtt:
  sensor:
    - name: "Living Room Temperature"
      state_topic: "zigbee2mqtt/Zigbee Thermostat Living Room ZWT198"
      unit_of_measurement: "°C"
      value_template: "{{ value_json.local_temperature }}"
      device_class: temperature

Save the file and restart Home Assistant to apply the changes.

Verify Sensor Availability in Home Assistant

After restarting Home Assistant, go to Developer Tools > States. Search for the sensor named sensor.living_room_temperature and verify that its value matches the current temperature measured by the thermostat.

Integrating the Temperature into a Home Assistant Card

To display the temperature on your Home Assistant dashboard, you can add an appropriate card. For instance, to show the current temperature, you might use the Sensor Card:

type: sensor
entity: sensor.living_room_temperature
name: Living Room Temperature

For a graphical representation of temperature trends, the History Graph Card is suitable:

type: history-graph
entities:
  - sensor.living_room_temperature
title: Living Room Temperature History
hours_to_show: 24
refresh_interval: 60