Attention Makers


Save $500+/year in utilities with a microcontroller


I save $500+/year just by modifying how the existing thermostat, dual output gas furnace and electric water heater operate using a separate inexpensive controller. It reduced my gas consumption per degree day by 33%. The water heater is controlled as well so it's only on at night just before use. Both can be monitored and controlled from a web page. The project is described at


The Purpose

In cold locations the furnace must be sized for worst case coldest temperature. This means for most of the year it operates at a small fraction of it's output by cycling on and off to meet a thermostat narrow temperature range. This modification let's the temperature vary more for more efficient, longer furnace run times. Also includes an electric water heater timer so it's only on at lower cost power time of use. Both changes are not noticeable but save $500+/year for $25 in components.

The Technology

I used $25 in components including a $4 Nodemcu wifi microcontroller board based based on the ESP8266 chip. This allows wireless uploads and monitor and control from a web page.

Additional Details

The Nodemcu device replaces an Arduino Uno which has been controlling these modifications since Feb 2017. My gas consumption per heating degree day is down 33% from 0.6 to 0.4 cubic metre per heating degree day.

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