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

June 09, 2021

When you’re looking for methods to lower heating and cooling expenses, getting a smart thermostat is an intelligent decision. These devices learn your temperature preferences and routine and then develop an energy-efficient schedule that fits. What’s even better is that you can regulate and monitor your settings from nearly anywhere with your phone, whether you’re relaxing in bed or on the go. (You might even be eligible for a free smart thermostat depending on rebate programs from your utility company in Kearney.)

Most of the time, hooking up a smart home thermostat with the assistance of Thurston Heating & Air Conditioning is an uncomplicated task if you have a new residence. But what if your residence is older or doesn’t have the right wiring? Can you still install a smart thermostat without C wire? We’ll help you demystify the process so you can pick the recommended 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 run on batteries. When you’re upgrading to a smart thermostat, you’ll find that many have to have 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 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 thinking 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. Make sure the C wire isn’t tucked in the wall. If you can’t find one, we may be able to install 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 just 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 won’t work and you don’t want to install 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 your needs.

Nest says its thermostats are created to consume very little power and can frequently share it with your heating and cooling system. However, you may need to have a professional like Thurston Heating & Air Conditioning 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 includes a C wire adaptor. So, you’re covered if you don’t have a thermostat C wire.

Trust Thurston Heating & Air Conditioning for Your Smart Thermostat Installation Needs

At Thurston Heating & Air Conditioning, we’re always looking for methods to keep you cozier while keeping utility costs low. If you have questions about installing a smart thermostat without a C wire, reach us at 308-624-3485. We can help you pick the right model for your house and even put in new wiring if necessary.