Help templating... my Hassos will serve me nice bath water... every morning

Installation Home Assistant OS
1

I have a solar panel for raise my water bath temperature, this panel have an electric resistance to increase temperature when need it

So, I already have a sonoff TH16 to control it.
Temperature sensor inside water, and the same sonoff control de electric resistance

I want to define the time to bath, and the water temperature at that time
I already know the temperature raise 0,25ºC every minute when the resistance is on…

So, I’m sure me HA can do it… but I’m not so good templating HA

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my first step is take the HH.MM needed to put resistance on

actual T= 58,4ºC ; objective T=65ºC

so (65-58,4)/0,25 = 26,4 »» 00:26 (26min on)

automations.yaml

- id: '1586516921111'
  alias: Update Tempo Aquecer Banho
  description: ''
  trigger:
  - minutes: /1
    platform: time_pattern
    seconds: '0'
  condition: []
  action:
  - service: input_datetime.set_datetime
    data_template:
      entity_id: input_datetime.tempo_aquecer_banho
      time: '{% set o = states('input_number.banho_temp') %} {% set r = states('sensor.sonoff_1000cf529b_temperature')
        %} {% set t = (o-r)/0.25 %} {{ t|timestamp_custom("%H:%M",True) }}'

Every minute HA will check and calculate for how long it need to be on.
AND THIS IS NOT WORKING, what’s wrong?

… after that the strategy is subtract this time to target HH:MM bath
and trigger on the resistance…

Any other ideas?
any help…

THANKS
GP

2

Try this version of the time template:

  - service: input_datetime.set_datetime
    data_template:
      entity_id: input_datetime.tempo_aquecer_banho
      time: >
        {% set o = states('input_number.banho_temp') | float %}
        {% set r = states('sensor.sonoff_1000cf529b_temperature') | float %}
        {% set t = (o-r)/0.25 %}
        {{ (t if t > 0 else 0) | timestamp_custom("%H:%M:%S", False) }}

Screenshot from 2020-10-07 17-56-27

I think you need to multiply the value by 60 (to get minutes) because the result, a timestamp, is in seconds.

EDIT

Enhanced last line of the template to compensate for negative values.

3

Thank you 123 Taras
with your code it works great.
i only did a IF beaucause of the negative value… to force Zero when the diference result in negative value…

thank you again

4

If there’s a possibility of the calculation producing a negative value, change the template’s last line to this:

        {{ (t if t > 0 else 0) | timestamp_custom("%H:%M:%S", False) }}

I have updated my previous post with this enhancement.