Most smart thermostats today that are Wi-Fi enabled or have a color touch screen may require constant power through a thermostat C-wire. This ensures your thermostat has a continuous flow of power to function properly. There may be a few smart thermostat models that don’t require a C-wire and can operate with batteries. You should always ensure proper wiring as needed for your HVAC system and corresponding thermostat (with or without a C-wire). Check your HVAC system compatibility to see if you need a C-wire for your smart thermostat.
This common wire kit eliminates the need to run a new wire throughout your home. Installation is easy. Watch the videos below for more info.
For use with Sensi Smart Thermostat and Sensi Touch Smart Thermostat.
Does not work with 2-wire systems
For the Sensi™ Smart Thermostat, a common wire (C-wire) is required for heat only systems, cool only and heat pump systems.
For the Sensi™ Smart Touch Thermostat, all system types require a common wire (C-wire).
C-wire help made simple.
Do I need a C‑wire?
If you're wondering what a C-wire is or how to look for one, you’ve come to the right place. Our step-by-step videos will guide you through the process and answer all your questions.
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.
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 as a C-wire
If you can not find an unused wire or common wire, you can also use for fan wire or G-wire as a common wire. This video serve as a second option in common wire installation.
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.