How can I mirror a device value to other devices based on state change

Configuration
1

I’m a week into my HA ownership, moving over from Homeseer - I’m learning so much and really enjoying it. Thanks to the community for all their efforts and investment.

I’ve spent way too much of today trying to automate my heating and would really appreciate some help. I have a Nest thermostat controlling my central heating, and would like that whenever the target Nest temperature (climate.hallway) changes, that temperature change is sync’d to my electric underfloor heating (UFH).

There are three UFH zones as follows (climate.z_wave_thermostat, climate.z_wave_thermostat_2 and climate.z_wave_thermostat_3), in an ideal world I would like the flexibility to vary the temperatures +/- a few degrees from the Nest target temperature.

I’ve struggled to work out exactly the best way to make this happen - I’ve explored automations, tried the UI, looked at helpers and trawled many forum posts. Based on my reading I’ve constructed this in the Template Editor and it returns the result I’m expecting (Nest temp - 2 degrees and the example target here being one of my UFH zones):

alias: Sync Thermostats
trigger:
  - platform: state
    entity_id: climate.hallway
    attribute: temperature
condition: []
action:
  - service: sync_thermostats
      temperature: "{{ state_attr('climate.hallway','temperature') | float(state) -2 }}"
          target:
      entity_id: climate.z_wave_thermostat_2

I’ve got part way there, but I really don’t know what to do next and I’m not convinced that I’m using the easiest method or best tool for the job, based on my target end-state.

I used an add-on/plugin to achieve this on Homeseer so wondering whether a similar approach is needed. Any advice or pointers would be very much appreciated. Thank you.

2

I’m not familiar with this service, typically to set a temperature on a thermostat you’d use climate.set_temperature.

3

like above and you need to take care of the yaml a bit more:

action: climate.set_temperature
target:
  entity_id: climate.z_wave_thermostat_2
data:
  temperature: >
    {{state_attr('climate.hallway','temperature') | float(0) -2 }}

you can test that out in the service actions dev tools. it will automatically create the correct syntax if you first use the UI method and then click Yaml

Note that your template has an odd state default value in the | float(state) filter. set that to a real number.
I cant imagine that state didn’t throw an error in the dev tools template?

you could make it a bit more controllable from the Frontend dashboard if you’d use an input_number for the -2. that would allow you to set in in the frontend, and not have to edit the automation

 {{state_attr('climate.hallway','temperature') | float(0) - states('input_number.calibrate_temperature')|float(0) }}

and can even make that negative and positive, in which case I’d flip the operator to + :wink:

Scherm­afbeelding 2024-09-21 om 23.13.57
Scherm­afbeelding 2024-09-21 om 23.13.571160×1210 43.1 KB

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4

Thank you. I’ve corrected it…and have so much to learn!

5

Thank you very much for the explanation and advice. With your help I have now managed to create three different actions, one for each target device, and I’ve “hard coded” the temperature differential I require in each. It gets me where I want to be for the moment…

However, I really like the idea of being able to control from the Front End as you describe. I have managed to create the “Calibrate Temperature” helper as per your screenshot, but are you able to provide a quick guide as to what steps I need to follow in order to make it more user-friendly as you describe?

Thank you again for your help.

6

just add it to a card in your dashboard where you need it most, eg next to your climate entities, nothing more. In take it you wouldnt want to keep changing it daily :wink:

(ofc also add the line in your automations, so these actually use the input_number…)

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7

Where did this code come from?

8

If you mean the code included in my original post, it’s something that I put together based on reading lots of different forum messages - I realise now it was full of errors…I’m still learning :roll_eyes:

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