This Old Oil-Burning Boiler Gets an Internet of Things Upgrade with an Espressif ESP8266
Clever power arrangement charges a hidden battery when the boiler is active, combining power input and monitoring in one.
Semi-pseudonymous maker "nbolton," hereafter simply "Bolton," has modernized an old oil-burning boiler to provide monitoring for when a new delivery of oil might be required — using an Espressif ESP8266 microcontroller.
"My simple invention effectively just monitors the AC line for voltage (to see if it's 0V or 240V), but I used a little trick," Bolton explains. "When the oil boiler's burner turns on, 240 VAC input powers the 5V AC/DC, and in turn powers the MCU while charging a battery (hidden behind the MCU). The output of the AC/DC is connected to a pin on the MCU (via a voltage divider) so that it can tell when the burner is on. When the AC power is cut, the battery keeps powering the MCU. I log how long the boiler has been burning oil to estimate how long until I need to order an oil delivery."
The heart of the system is an Espressif ESP8266, which provides both a microcontroller core running custom C code Bolton wrote for the project and Wi-Fi connectivity to the home network. This lives on a piece of prototyping board and connects to the boiler's power line — providing both a means of monitoring when the boiler is drawing power and, thanks to the hidden battery, when it isn't.
"[I'm] currently using Blynk for visualization," Bolton explains of the data provided by the device, "but planning to set up Home Assistant. Sometimes its nice to have old stuff so you can modernize it. Soon it will die and my invention will be obsolete. Oh well! It was fun to make."
More information is available on Bolton's Reddit post; the source code and schematics have not been publicly released.
