Automation based on state change of a group of similarly named entries

Configuration
1

Dear community:

I’m beginner of HA and trying to migrate from my current system (OpenHAB + HomeBridge) to HA. I have managed to migrate most of the devices/entries to HA and really love the simplicity of configuration. Now I start to look into some automations and would like some help.
So basically I have a group of similarly named climate entries:

  - climate.bathroom_thermostat
  - climate.bedroom_closet_thermostat
  - climate.bedroom_thermostat
  .......

Each climate has the following attributes:

hvac_modes: heat
min_temp: 10
max_temp: 35
current_temperature: 21.6
temperature: 20
hvac_action: idle
friendly_name: Bathroom Thermostat
supported_features: 1

I’d like to create an automation based on change of attribute of any entry:

  • When current_temperature of any entry is above certain threshold, send a push notification
  • When hvac_action changes between idle - heat, calculate water temperature based on how many of the thermostats are in heat state. (the water temperature needs to be higher if more thermostats are in heat state).
    I have tried to create a group like below:
group_thermostats:
  name: "All Thermostats"
  entities:
    - climate.bathroom_thermostat
    - climate.bedroom_closet_thermostat
    - climate.bedroom_thermostat

But looks like I cannot subscribe to change of attribute of the individual thermostats, and I don’t want to define an automation for each thermostat. How can I do it in a smart way in HA?
Your hint or suggestion is highly appreciated!

2

I used the GUI to create this code.

description: ""
mode: single
triggers:
  - trigger: state
    entity_id:
      - climate.david
      - climate.sovrum
    attribute: current_temperature
conditions: []
actions: []

It seems to accept it but I’m not sure it will work.

I changed the code to:

alias: aaaaaaaaaaa
description: ""
triggers:
  - trigger: state
    entity_id:
      - climate.david
      - climate.sovrum
    attribute: current_temperature
conditions: []
actions:
  - action: notify.mobile_app_andreas
    metadata: {}
    data:
      message: boo
mode: single

and it sent me a message when I used set state in developer tools.
It seems to work.