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Showing posts from February, 2019

IoT HVAC Monitor

I built this project in July of 2018 and posted it on


IoT HVAC MonitorMonitors the fan speed, on/off cycles, temperature, and humidity of my HVAC system and posts data to
Parts used: SparkFun ESP8266 Thing - Dev BoardDHT11 Temperature & Humidity Sensor (4 pins)3.7 V LiPo BatteryResistor 1k ohmBreadboard (generic)Dell X77M FanI built this project for two reasons. (1) I've been looking for an excuse to play around with IoT, and with the ESP8266 in particular. (2) My electric bill has been steadily increasing and I wanted to see how often my HVAC system was cycling on and off (and at what temperature).
I figured I could monitor on/off cycles by attaching a small DC fan motor to the return air grill. When the HVAC unit turns on, the airflow will cause the fan to turn; acting as a generator. I can then read the voltage generated by the fan motor by connecting it to an analog input…