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

June 09, 2021

When you’re wanting approaches to decrease energy expenses, installing a smart thermostat is a wise move. These devices adjust to the temperatures you like and routine and then create an energy-efficient schedule that matches. 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 provider in Pflugerville.)

In most instances, installing a smart home thermostat with the help of Evenaire Heating & Air Conditioning is a simple process if you have a more modern residence. But what if your house is older or doesn’t have the proper wiring? Can you still add a smart thermostat without C wire? We’ll help you navigate the process so you can select the correct thermostat and get energy savings for a long time.

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

Many programmable thermostats need batteries. When you’re switching to a smart thermostat, you’ll find that many require a C wire, or common wire, for power. If you don’t use 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. Remove the thermostat and find the wiring.
  3. If there are five or six multicolored wires, you have what’s needed for a smart thermostat. You might be pondering what color is the C wire on a thermostat—and the answer to that is often blue.
  4. If there are three or four thin multicolored wires, you’re close. Make sure the C wire isn’t rolled up in the wall. If you can’t find one, we may be able to add 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 use 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 best-selling 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 made to run on not a lot of power and can typically share it with your home comfort system. However, you may need to have a professional like Evenaire 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 frequently drained.

ecobee is compatible 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 Evenaire Heating & Air Conditioning for Your Smart Thermostat Installation Needs

At Evenaire Heating & Air Conditioning, we’re always on the lookout for methods to keep you more comfortable while keeping heating and cooling expenses low. If you want to learn more about installing a smart thermostat without a C wire, give us a call at 512-355-1482. We can help you select the right model for your home and even add new wiring if required.