Automation: trigger when x difference between two sensors

Configuration
1

Hi

I wanna create a automation that will trigger a ventilator when there is 2 °C difference between two temperature sensors.
But i can´t figure out how to make that condition?

2

You are looking fore a trigger, not for a condition.
Create a template sensor, that calculate the temperature difference. And use the new sensor as a trigger.

3

If you can use YAML:

- alias: Ventilator on-off control
  description: Turns on at 2°C difference, off under 1.5°C
  id: 740f1bb9-ff92-4388-9462-e05d9a6c2630
  trigger:
    - id: 'on'
      platform: template
      value_template: "{{ (states('sensor.temp_1')|float - states('sensor.temp_2')|float)|abs > 2 }}"
    - id: 'off'
      platform: template
      value_template: "{{ (states('sensor.temp_1')|float - states('sensor.temp_2')|float)|abs < 1.5 }}"
  action:
    - service: 'switch.turn_{{ trigger.id }}'
      entity_id: switch.ventilator