Saturday, January 09, 2016

Raspberry Pi Thermostat Instructions

Here are some details on how I put together my Raspberry Pi thermostat.

My apartment's thermostat uses a very simple mechanism to control the heater:

Connecting the red wire to the white wire turns on the heater. Near the center of the thermostat is a glass vial containing some mercury. If the vial tilts to the right the mercury creates a connection between the wires. I attached the two black wires on the bottom and use the Raspberry Pi to control the connection between the wires. The original thermostat remains fully functional: the heater will turn on if either the Raspberry Pi or the original thermostat signal it to turn on.

Materials used: The relay module controls the connection between the two heater wires. GPIO output from the Raspberry Pi can turn the connection on/off. The connection is off by default - even when the Raspberry Pi is powered off. I SSH into the Raspberry Pi to control the GPIO pin over the Internet.

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