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

June 09, 2021

When you’re seeking ways to decrease utility bills, getting a smart thermostat is an intelligent idea. These devices pick up on your favorite temperatures and routine and then develop an energy-efficient schedule to match. What’s even better is that you can adjust and keep an eye on your settings from just about anywhere with your phone, whether you’re lying in bed or away from home. (You might even be able to receive a free smart thermostat depending on rebate programs from your utility supplier in Tucson.)

In most instances, hooking up a smart home thermostat with the support of Ambient Air is an uncomplicated job if you have a newer home. But what if your residence is older or doesn’t have the proper wiring? Can you still install a smart thermostat without C wire? We’ll help you navigate the process so you can select the ideal thermostat and enjoy energy savings for years to come.

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

Many programmable thermostats run on batteries. When you’re upgrading to a smart thermostat, you’ll discover that many have to have a C wire, or common wire, for power. If you don’t have this wire, your new thermostat might cause your heating and cooling system to have malfunctions.

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

  1. Cut power to the thermostat at the breaker.
  2. Pull off the thermostat and find the wiring.
  3. If there are five or six multicolored wires, you have what you need for a smart thermostat. You might be pondering 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 nearly there. Make sure the C wire isn’t hidden in the wall. If you can’t find one, we may be able to put in 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 use a smart thermostat with an adaptor specifically for high-voltage systems. Or you may be able to install 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 might be a match for you.

Nest says its thermostats are created to consume not a lot of power and can frequently share it with your home comfort system. However, you may need to have a specialist like Ambient Air add a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re running into power problems or a battery that’s constantly drained.

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

Trust Ambient Air for Your Smart Thermostat Installation Needs

At Ambient Air, we’re always looking for methods to keep you more comfortable while keeping heating and cooling expenses low. If you want to learn more about upgrading to a smart thermostat without a C wire, contact us at 520-201-3871. We can help you select the right model for your home and even install new wiring if required.