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

June 09, 2021

When you’re wanting ways to decrease heating and cooling expenses, getting a smart thermostat is an intelligent move. These devices adjust to the temperatures you like and routine and then develop an energy-efficient schedule that fits. What’s even better is that you can adjust and keep an eye on your settings from just about anywhere with your phone, whether you’re lying in bed or away from home. (You might even be able to receive a free smart thermostat depending on rebate programs from your utility provider in Los Angeles.)

In most instances, hooking up a smart home thermostat with the help of AZ Air Conditioning and Heating is a simple task if you have a new house. But what if your home is older or doesn’t have the proper wiring? Can you still have a smart thermostat without C wire? We’ll help you figure out the process so you can select the right thermostat and enjoy 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 making the move to a smart thermostat, you’ll discover that many need a C wire, or common wire, for power. Without this wire, your new thermostat may cause your heating and cooling system to have glitches.

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

  1. Turn 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 you need 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 close. Ensure the C wire isn’t rolled up inside 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 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 most popular brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats might be an option for you.

Nest says its thermostats are made to require minimal power and can frequently share it with your home comfort system. However, you may need to have a pro like AZ Air Conditioning and Heating add 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 works 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.

Trust AZ Air Conditioning and Heating for Your Smart Thermostat Installation Needs

At AZ Air Conditioning and Heating, we’re always looking for ways to keep you cozier while keeping heating and cooling expenses inexpensive. If you want to learn more about upgrading to a smart thermostat without a C wire, give us a call at 800-296-5088. We can help you pick the right model for your house and even put in new wiring if required.