Suggestions on how to turn of a device after certain time without using delay

2

I assume you mean ‘turn off’ after a delay?

Your first action turns it on.

If so, use two automations:

Turn on

alias: VVB Av etter en time
description: ''
trigger:
  - platform: time
    at: input_datetime.billigtime1
  - platform: time
    at: input_datetime.billigtime2
  - platform: time
    at: input_datetime.billigtime3
  - platform: time
    at: input_datetime.billigtime4
  - platform: time
    at: input_datetime.billigtime5
  - platform: time
    at: input_datetime.billigtime6
  - platform: time
    at: input_datetime.billigtime7
  - platform: time
    at: input_datetime.billigtime8
  - platform: time
    at: input_datetime.billigtime9
  - platform: time
    at: input_datetime.billigtime10
  - platform: time
    at: input_datetime.billigtime11
  - platform: time
    at: input_datetime.billigtime12
condition: []
action:
  - service: switch.turn_on
    target:
      entity_id: switch.varmtvannstank
  - service: notify.mobile_app_thomas_mobil
    data:
      title: 'VVB PÅ Billig '
      message: '{{now()}}'
mode: single

Turn off:

alias: Turn off after 59 minutes
trigger:
  - platform: state
    entity_id: switch.varmtvannstank
    to: 'on'
    for:
      minutes: 59
action:
  - service: switch.turn_off
    target:
      entity_id: switch.varmtvannstank
  - service: notify.mobile_app_thomas_mobil
    data:
      title: VVB AV 59min
      message: '{{now()}}'
mode: single

This trigger off for time will be reset and start counting again if automations are reloaded or when Home Assistant restarts.

If the time is super critical you could start a timer in the “turn on” automation and use the timer finishing as the trigger for your off automation. The timer will not be affected by automation reloads and there is a method to restore active timers after a restart, see: https://community.home-assistant.io/t/restore-active-paused-timers-after-a-restart/274439