trv_external_temperature.yaml

blueprint:
  name: Universal TRV External Temperature Control
  description: >
    This automation allows any TRV (Thermostatic Radiator Valve) to use temperature readings from an external sensor. 
    Whenever the temperature sensor reports a new value, it is sent to the TRV's external temperature input for more accurate climate control.
    
    **Requirements:**
    - Your TRV must have a number entity to set the external temperature value
  domain: automation
  source_url: "https://gist.github.com/JakeCowton/314b1a4bf33934a556ab71952c8a4461"

  input:
    external_temp_sensor:
      name: External Temperature Sensor
      description: Select the temperature sensor that will provide temperature readings to the TRV.
      selector:
        entity:
          filter:
            domain: sensor
            device_class:
              - temperature

    trv_external_temp_input:
      name: TRV External Temperature Input
      description: Select the number entity that sets the external temperature value on the TRV.
      selector:
        entity:
          filter:
            domain: number

    stop_on_unavailable:
      name: Stop Updates When Sensor Unavailable
      description: If enabled, stops updating the TRV when the external sensor becomes unavailable or reports invalid values.
      selector:
        boolean:
      default: true

mode: single
max_exceeded: silent

variables:
  external_temp_sensor: !input external_temp_sensor
  trv_external_temp_input: !input trv_external_temp_input
  stop_on_unavailable: !input stop_on_unavailable

trigger:
  - trigger: state
    entity_id: !input external_temp_sensor

action:
  # Check if external temperature sensor is available
  - if:
      - condition: template
        value_template: >-
          {{ stop_on_unavailable and (
             is_state(external_temp_sensor, "unavailable") or 
             is_state(external_temp_sensor, "unknown") or
             states(external_temp_sensor) in ['', none]) }}
    then:
      - action: system_log.write
        data:
          level: warning
          message: "External temperature sensor {{ external_temp_sensor }} unavailable. Skipping TRV update."
          logger: Universal TRV External Temperature
      - stop: External temperature sensor unavailable

  # Set the external temperature value
  - action: number.set_value
    data:
      value: "{{ states(external_temp_sensor) | float(0) | round(1) }}"
    target:
      entity_id: "{{ trv_external_temp_input }}"