A year ago, we moved into our new home in Redmond and the house furnace was still controlled by an ancient thermostat, built using Cold War era technology and I set out to replace it with something better… While an off-the-shelf thermostat would have worked as a replacement, I wanted more!

• I wanted to be able to control the temperature of the house from anywhere using a web browser
• I wanted to get interesting energy consumption statistics to measure the effectiveness of our home improvements

Last week, I finally achieved the first step and here’s what the interface looks like right now:

Temp=20.50C / 68.89F Heat=ENABLED Relay=OFF Heat Timer=0 mins Turn Heat Timer ON or OFF Disable or Enable Heat

The thermostat is built with an Arduino Duemilanove board, upgraded with an Atmega328 chip, a WiShield board, a Maxim DS1822 temperature sensor and a 5v relay to switch the furnace on/off.

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The code, in progress, is available here