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

June 09, 2021

When you’re looking for ways to decrease utility bills, installing a smart thermostat is a wise move. These devices adjust to your favorite temperatures and routine and then develop an energy-efficient schedule that fits. What’s even better is that you can regulate and watch your settings from nearly anywhere with your phone, whether you’re relaxing in bed or out and about. (You might even be able to receive a free smart thermostat depending on rebate programs from your utility company in Lodi.)

Most of the time, installing a smart home thermostat with the support of Tokay Heating and Air Conditioning is a straightforward task if you have a newer 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 navigate the process so you can select the recommended thermostat and get energy savings for a long time.

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

The majority of programmable thermostats use batteries. When you’re making the move to a smart thermostat, you’ll find that many require a C wire, or common wire, for power. Without this wire, your new thermostat could cause your heating and cooling system to have malfunctions.

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

  1. Switch off power to the thermostat at the breaker.
  2. Take off 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 typically blue.
  4. If there are three or four thin multicolored wires, you’re close. Check the C wire isn’t rolled up 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 run your new thermostat without one.
  5. If you have two thick wires, you may be able to install a smart thermostat with an adaptor designed 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 isn’t right and you don’t want to replace it.

Do Nest or ecobee Need a C Wire?

Two of the best-selling brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats might be a fit for you.

Nest says its thermostats are designed to consume not a lot of power and can typically share it with your home comfort system. However, you may need to have a professional like Tokay Heating and Air Conditioning install a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re having power problems or a battery that’s frequently drained.

ecobee connects 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.

Rely on Tokay Heating and Air Conditioning for Your Smart Thermostat Installation Needs

At Tokay Heating and Air Conditioning, we’re always looking for methods to keep you more comfortable while keeping utility bills low. If you have questions about upgrading to a smart thermostat without a C wire, reach us at 209-257-3156. We can help you choose the right model for your residence and even add new wiring if required.