WiFi Waterbed and Freezer Temperature Control

Our chest freezer suddenly died as well. With the same components I turned a mini fridge into a freezer until we get a new one. The thermostat wouldn't go low enough. So I replaced it with a digital temperature sensor and microcontroller. Clock is used to delay restart for 200 seconds after power failure or compressor OFF. Refrigeration compressors need to be off for some time before restarting so they don't try to start under running pressure. Added a 12V pc fan inside and a USB fan blowing on the compressor.

Implemented Away mode described above. Bedside light turns on for a random time while we are away. Waterbed heater also turns totally off and turns back on 2 days before we return since it takes a long time to heat from room temp back to 29C. It typically only loses 2C in 12 hours when it's off 7 am to 7 pm but it takes 3 hours to get back to 29C. I also record waterbed temp every hour now using Adafruit free MQTT. I highly recommend this method to record data to the cloud. Once you get the hang of it, it's very easy to create a cloud based HMI and storage and display of data. I can see the waterbed turning back on and heating up from anywhere now.