Splitting energy sensor based on value

The error (or problem is a better word) is that after startup of HA before the first trigger it starts with the wrong value. So I want to have the correct value immediately after the power value has been measured.

it will only do that when the there is a threshold change during the restart. So e.g. someone was warming water when you pressed the restart button, and is no longer doing that when HA started again. Otherwise it will be on the right value after the restart.

To mitigate that, change the automation to:

- id: '123452135311'
  triggers:
  - alias: trigger on every state change of the power sensor
    trigger: state
    entity_id: sensor.wp_power
    not_to: unavailable
  - alias: trigger on start of Home Assistant
    trigger: homeassistant
    event: start
  actions:
    - alias: determine which state the select entity should be on
      if:
        - alias: Heatpump power value is below 500
          condition: numeric_state
          entity_id: sensor.wp_power
          below: 500
      then:
        - alias: Set select entity to Verwarming
          action: select.select_option
          target:
            entity_id: select.heatpump
          data:
            option: Verwarming # make sure this matches the option from the select dropdown for verwarming
      else:
        - alias: Set select entity to Tapwater
          action: select.select_option
          target:
            entity_id: select.heatpump
          data:
            option: Tapwater # make sure this matches the option from the select dropdown for tapwater

Thanks a lot again! Where can I find a good training to build these scripts myself? To me it looks like the Home Assistant documentation is quite limited.

Triggers are documented here: https://www.home-assistant.io/docs/automation/trigger/
Conditions (not used in this automation) are documented here: https://www.home-assistant.io/docs/automation/condition/
Actions are documented here: https://www.home-assistant.io/docs/scripts/