Trigger automation on temp_sensor value below climate value

Hello,

I hope someone can help me.

I have a heater by Mill. It has a temp sensor inside, so it will disable heating if the desired temperature is reached. The problem is, that the heater sits on a cold wall. The room is therefore already warm enough, but the sensor inside the heater says it still needs to heat.
I have a separate temp sensor in this room. Is it possible to disable the heater if the desired temperature set in the heater is reached (but evaluated by the separate sensor - not the one inside the heater).

Is my problem clear? :sweat_smile:

You could create an automation to turn off the heater when the temperature changes that checks it against the sensor, something like this (assuming your heater is a climate device called heater and your sensor is a sensor device called room_temp):

{% if float(state_attr('climate.heater', 'temperature'),0) < float(states('sensor.room_temp'), 0) %}
  ... code to turn off the heater such as setting the HVAC mode of the climate device or lowering the set temp, etc
{% endif %}