I Want a Smart Thermostat but Don't Have a C Wire - Now What?

June 09, 2021

When you’re wanting ways to reduce heating and cooling expenses, installing a smart thermostat is a smart idea. These devices learn your temperature preferences and routine and then make an energy-efficient schedule to match. What’s even better is that you can change and keep an eye on your settings from nearly anywhere with your phone, whether you’re lying in bed or on the go. (You might even be able to get a free smart thermostat depending on rebate programs from your utility supplier in Lafayette.)

In most instances, installing a smart home thermostat with the help of AC Sales is an uncomplicated task if you have a more modern house. But what if your home is older or doesn’t have the correct wiring? Can you still add a smart thermostat without C wire? We’ll help you demystify the process so you can pick the correct thermostat and enjoy energy savings for many years.

What Is a C Wire and What Does It Do on a Thermostat?

The majority of programmable thermostats need batteries. When you’re upgrading to a smart thermostat, you’ll learn that many require a C wire, or common wire, for power. If you don’t have this wire, your new thermostat could cause your heating and cooling system to have glitches.

You can find out if you have a C wire by doing the following:

  1. Turn off power to the thermostat at the breaker.
  2. Remove the thermostat and look at the wiring.
  3. If there are five or six multicolored wires, you have what you need for a smart thermostat. You might be thinking what color is the C wire on a thermostat—and the answer to that is often blue.
  4. If there are three or four thin multicolored wires, you’re nearly there. Check the C wire isn’t rolled up inside the wall. If you can’t find one, we may be able to put in one for you or you may be able to operate your new thermostat without one.
  5. If you have two thick wires, you may be able to use a smart thermostat with an adaptor designed for high-voltage systems. Or you may be able to operate a battery-powered smart thermostat, like the Lux Geo Wi-Fi Thermostat, if your wiring is incompatible and you don’t want to put in new wiring.

Do Nest or ecobee Need a C Wire?

Two of the most popular brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats could work for your home.

Nest says its thermostats are designed to run on minimal power and can often share it with your heating and cooling system. However, you may need to have a specialist like AC Sales put in a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re experiencing power problems or a battery that’s always drained.

ecobee is compatible with 24-volt systems (ones with three to six thermostat wires) and has a C wire adaptor. So, you’re good if you don’t have a thermostat C wire.

Depend on AC Sales for Your Smart Thermostat Installation Needs

At AC Sales, we’re always looking for ways to keep you comfier while keeping heating and cooling bills low. If you want to know more about installing a smart thermostat without a C wire, contact us at (337) 234-2345. We can help you select the right model for your home and even install new wiring if needed.