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

June 09, 2021

When you’re looking for ways to decrease utility bills, getting a smart thermostat is a smart idea. These devices learn your favorite temperatures and routine and then make an energy-efficient schedule that matches. What’s even better is that you can change and monitor your settings from nearly anywhere with your phone, whether you’re sitting in bed or on the go. (You might even be eligible for a free smart thermostat depending on rebate programs from your utility provider in Norco and St. Charles Parish.)

In most instances, adding a smart home thermostat with the assistance of Mayeuxs AC & Heating is a simple task if you have a more modern house. But what if your residence is older or doesn’t have the correct wiring? Can you still have a smart thermostat without C wire? We’ll help you figure out the process so you can choose the recommended thermostat and receive 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 making the move to a smart thermostat, you’ll find that many need a C wire, or common wire, for power. If you don’t have this wire, your new thermostat may cause your heating and cooling system to have glitches.

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

  1. Switch off power to the thermostat at the breaker.
  2. Pull off the thermostat and look at the wiring.
  3. If there are five or six multicolored wires, you have what’s needed for a smart thermostat. You might be wondering what color is the C wire on a thermostat—and the answer to that is typically blue.
  4. If there are three or four thin multicolored wires, you’re almost there. Ensure the C wire isn’t tucked inside the wall. If you can’t find one, we may be able to install one for you or you may be able to use your new thermostat without one.
  5. If you have two thick wires, you may be able to install a smart thermostat with an adaptor specifically for high-voltage systems. Or you may be able to use a battery-powered smart thermostat, like the Lux Geo Wi-Fi Thermostat, if your wiring isn’t right and you don’t want to replace it.

Do Nest or ecobee Need a C Wire?

Two of the top brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats could be a fit for your needs.

Nest says its thermostats are designed to need minimal power and can typically share it with your heating and cooling system. However, you may need to have a pro like Mayeuxs AC & Heating install a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re experiencing power problems or a battery that’s frequently drained.

ecobee connects with 24-volt systems (ones with three to six thermostat wires) and comes with a C wire adaptor. So, you’re taken care of if you don’t have a thermostat C wire.

Depend on Mayeuxs AC & Heating for Your Smart Thermostat Installation Needs

At Mayeuxs AC & Heating, we’re always looking for ways to keep you cozier while keeping energy expenses reasonable. If you want to learn more about switching to a smart thermostat without a C wire, contact us at (985) 764-2426. We can help you select the right model for your house and even put in new wiring if needed.