For Sensi smart thermostat or Sensi Lite smart thermostat, a common wire (c-wire) is required for heat only systems, cool only and heat pump systems.
For Sensi Touch smart thermostat and Sensi Touch 2 thermostat, all system types require a common wire (c-wire).
C-wire help made simple.
Start with the first video and follow along in order until you find the solution that’s right for you.
Options for adding a common wire
Basic c-wire introduction
Learn about the basics of common wire installation by watching this video. You will also be guided on how-to and when-to connect c-wires to thermostats. It also shows three different scenarios to choose which methods works best for you.
Using an extra unused wire as a "c-wire"
Finding and using an unused wire as a c-wire
Sensi Thermostats require a common wire to complete installation. This video will guide you in checking if you have a common wire, or an unused common wire from your previous thermostat that you can use to install your Sensi Thermostat.
Using the g-wire(fan wire) as a c-wire
Using the g-wire as a c-wire
If you can't find an unused wire or common wire, you can also use the fan wire or g-wire as a common wire. This video serves as a second option in common wire installation.
Sensi | Install Common Wire Kit
Install Common Wire Kit
Installing Common Wire Maker Kit
If there is not an extra unused wire running from the thermostat to the furnace, and using the g-wire as a common wire is not an option, in most cases, installing a Common Wire Maker Kit is the best solution.
