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

June 09, 2021

When you’re wanting methods to lower energy costs, installing a smart thermostat is a smart move. These devices adjust to your favorite temperatures and routine and then make an energy-efficient schedule that fits. What’s even better is that you can adjust and monitor your settings from almost 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 company in Omaha.)

In many instances, hooking up a smart home thermostat with the assistance of The Frazier Company is a simple job if you have a new residence. But what if your residence is older or doesn’t have the proper wiring? Can you still have a smart thermostat without C wire? We’ll help you navigate the process so you can select the recommended thermostat and enjoy energy savings for years to come.

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

Many programmable thermostats use batteries. When you’re making the move to a smart thermostat, you’ll find that many have to have a C wire, or common wire, for power. If you don’t use this wire, your new thermostat might cause your heating and cooling system to have malfunctions.

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

  1. Cut 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 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. Check the C wire isn’t tucked inside 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 use a battery-powered smart thermostat, like the Lux Geo Wi-Fi Thermostat, if your wiring is incompatible 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 could be a match for you.

Nest says its thermostats are created to need very little power and can typically share it with your HVAC system. However, you may need to have a pro like The Frazier Company put in a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re running into power problems or a battery that’s always 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.

Rely on The Frazier Company for Your Smart Thermostat Installation Needs

At The Frazier Company, we’re always on the lookout for approaches to keep you comfier while keeping energy costs low. If you have questions about upgrading to a smart thermostat without a C wire, contact us at 402-628-0206. We can help you select the right model for your residence and even install new wiring if needed.