I Want a Smart Thermostat but Don't Have a C Wire - What Are My Options?

June 09, 2021

When you’re looking for ways to reduce heating and cooling expenses, getting a smart thermostat is a wise decision. These devices adjust to your temperature preferences 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 able to receive a free smart thermostat depending on rebate programs from your utility supplier in Ellsworth.)

In many instances, installing a smart home thermostat with the help of Walter's-Eaton's Electric, Plumbing, Heating & AC is an uncomplicated process if you have a new home. But what if your house is older or doesn’t have the right wiring? Can you still have a smart thermostat without C wire? We’ll help you figure out the process so you can select the ideal 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 making the move to a smart thermostat, you’ll learn that many have to have a C wire, or common wire, for power. If you don’t use this wire, your new thermostat could cause your heating and cooling system to malfunction.

You can find out 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 check the wiring.
  3. If there are five or six multicolored wires, you have what’s required 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 nearly there. Ensure the C wire isn’t tucked within 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 run 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 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 needs.

Nest says its thermostats are created to consume very little power and can typically share it with your HVAC system. However, you may need to have a pro like Walter's-Eaton's Electric, Plumbing, Heating & AC install a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re running into power problems or a battery that’s frequently drained.

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

Trust Walter's-Eaton's Electric, Plumbing, Heating & AC for Your Smart Thermostat Installation Needs

At Walter's-Eaton's Electric, Plumbing, Heating & AC, we’re always looking for methods to keep you comfier while keeping utility costs reasonable. If you want to know more about upgrading to a smart thermostat without a C wire, give us a call at 715-318-6728. We can help you pick the right model for your home and even put in new wiring if necessary.