The Atag integration allows Home Assistant to connect to Atag One thermostats, reporting and setting its status. The integration implements the following platforms:

  • Climate
  • Water heater
  • Sensor


To add the Atag integration to your Home Assistant instance, use this My button:

Configuration Variables

host string Required

Atag hostname or IP address.

port integer (Optional)

API Port. Only change if you are connecting indirectly (e.g. through reverse proxy)


The Atag climate platform provides current and target temperature information for the heating system, boiler status and HVAC mode.

Integration services

This integration supports the following services (see Climate).

  • set_temperature
  • set_hvac_mode
    • heat for thermostat mode
    • auto for weather-based mode
  • set_preset_mode
    • Manual enable manual operation
    • Auto enable schedule based operation
    • Extend delay the next scheduled temperature update by the default extend period
    • away enable the vacation mode for 1 day or until another preset is activated
    • boost enable fireplace mode
`HVAC mode Auto` (Weather based) should not be confused with `Preset mode Auto` (Scheduled, thermostat mode). Currently selection of custom timeframes in Extend, Away and boost modes is not supported. The default settings can be changed on the device.

Water heater

The water heater reports current and target temperature for Domestic Hot Water demand, as well as boiler status (heating or idle). This can be used to detect hot water demand, such as a running shower or tap water. Setting target values is currently not supported.


Not all metrics reported by the One are part of either the Water-Heater or Climate platform. Additional sensors are added to Home Assistant to monitor these metrics, which can be disabled in the UI if preferred. Navigate to Configuration, Entities and select the entity you wish to disable. The following sensors will be added to Home Assistant:

Sensors enabled by default

  • average_outside_temperature
  • burning_hours
  • ch_return_temperature
  • ch_water_pressure
  • ch_water_temperature
  • flame
  • outside_temperature
  • weather_status