Securing temperature control in greenhouse

Temperature is controlled by turing ON and OFF air heater that has it’s own temp sensor. That works, but should something fail there is a risk to overheat greenhouse or freeze the plants. So I have added ESP32 device with temp sensor and ESPHome that reports temp to HA. There is still risks that something will malfunction and I would like to minimize that risk, please help me getting my thinking right. Here are considerations.

  1. ESPHome reports temp to HA and I can add automation to call action if temp is out of defined range. I started with action to send Pushover message as it also plays short sound. However this requires notification volume to be high and I hate getting notification (email, facebook, etc) sounds, especially during the night, so it is set to OFF all the time on my phone. I have also tried action to set alarm clock, which worked fine for specified time, but I did not find how to start it NOW, when trigger is fired. I have then learned that I can use TTS action to play message on my phone loud. This is my current solution, will probably check if I can add Amazon Alexa too to this routine. I do miss however solution to switch it off. So if the temp is lower than set threshold, I will get that TTS message played continuesly, until I bring temp back to predefined range. My thought is to set a button in HA, that would be set as condition in automation, so pressing that button would kind of dissable action until I press that button again. Haven’t tried working with buttons in HA. Is that the way to go, or perhaps other thoughts?.
  2. ESP32 with ESPHome can malfunction. It could be ESP32 failure or it could mean no power supply (air heater is on the same power line, so it would not work either). Would be great to ping EPS32 every 15 minutes (or check if device is live some other way) and create an action if device is not responding. Not sure what is the best way to do that.
  3. HA is running on Raspberry Pi and there is a risk here also that it might malfunction. I have separate installation of HA on Proxmox server that is not actively used, but it is on. Would be great to use HA on Proxmox to check if Raspberry Pi HA is live and send the message (like is question 1) to me when it is off. Not sure about the method to do that, will keep reading, would be great to hear some suggestions.

If I manage to address all three above points, I believe I am covered, unless power supply is off for the whole house, but then I will probably notice without assistance from HA :slight_smile: