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This winter I noticed several times that the temperature at our church was not where it should be. Either the heat was on on a day when it was not in use or there was a chill on Sunday morning. Ours is not a large church and the thermostat is not out in the open. I do not suspect that people are altering the temperature so it could be that the system is having issues. I needed data to understand what is happening and to possibly take action.


ESP201 (white), DHT11 (blue), 6-12vdc to 3.3vdc converter (black)

I put together a couple of sensors using an ESP-201 (esp8266) and a DHT11. The DHT11 is not very accurate as compared to a DS1820, but it is good enough for my purposes.  I wrote a simple program for the ESP201 that will connect to the WiFi, read the temperature and send it via MQTT. This is repeated every 10 minutes.

On my server I have MQTT and Node-Red installed. I have setup the Node-Red to capture the temperature readings to a MySQL database for future analysis. I have also created a simple status page to see what the temperature readings are. Future plans would be to send an alert if the temperature is out of bounds.

Future enhancements might focus on monitoring the HCVAC system for run-time and energy consumption.

NodeRed screenshot

Node-Red screen shot