Automation to turn on device for 1 hour

Configuration
1

Hi all,

Here is my requirement:
I want to create an automation that switches on my immersion heater for one hour whenever I run the script.

Can someone help me define how to do this?

2

For a light :

  trigger:
  - entity_id: light.your_entity
    for: 01:00:00
    platform: state
    to: 'on'
  action:
  - data:
      entity_id: light.your_entity
    service: light.turn_off

Does not survive HA restarts if HA is restarted in that hour.