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

June 09, 2021

When you’re wanting ways to reduce energy expenses, upgrading to a smart thermostat is a wise idea. These devices adjust to the temperatures you like and routine and then develop an energy-efficient schedule to match. What’s even better is that you can regulate and watch your settings from nearly anywhere with your phone, whether you’re sitting in bed or on the go. (You might even be eligible for a free smart thermostat depending on rebate programs from your utility provider in Ballwin and St. Charles.)

Most of the time, installing a smart home thermostat with the assistance of Air Alliance Team is an uncomplicated task if you have a newer home. But what if your residence is older or doesn’t have the right wiring? Can you still have a smart thermostat without C wire? We’ll help you demystify the process so you can choose the ideal thermostat and enjoy energy savings for a long time.

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

The majority of programmable thermostats need batteries. When you’re upgrading 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 may cause your heating and cooling system to have malfunctions.

You can ascertain 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 find 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 often blue.
  4. If there are three or four thin multicolored wires, you’re almost there. Ensure the C wire isn’t tucked within the wall. If you can’t find one, we may be able to add 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 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 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 may be a fit for your needs.

Nest says its thermostats are created to need minimal power and can typically share it with your heating and cooling system. However, you may need to have a pro like Air Alliance Team 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 frequently drained.

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

Depend on Air Alliance Team for Your Smart Thermostat Installation Needs

At Air Alliance Team, we’re always on the lookout for ways to keep you more comfortable while keeping energy costs low. If you want to learn more about installing a smart thermostat without a C wire, give us a call at 636-206-4250. We can help you select the right model for your residence and even put in new wiring if needed.