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.

For Sensi™ Wi-Fi Thermostat, a common wire (c-wire) is required for heat only systems, cool only systems and heat pump without auxiliary heat. For Sensi™ Wi-Fi Touch 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.

Basic c-wire introduction

Learn about why you need a c-wire and your options for hooking one up.

Finding and using an unused wire as a c-wire

Find out if you have an extra wire and learn how to hook it up.

Using the g-wire as a c-wire

Learn how to use your fan wire as a c-wire.

Installing an Emerson Thermostat Common Wire Kit

If a thermostat common wire kit is needed, we’ll walk you through the installation process.

Emerson Common Wire Kit

Emerson common wire kit

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