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

June 09, 2021

When you’re wanting approaches to reduce utility costs, upgrading to a smart thermostat is a smart decision. These devices pick up on your favorite temperatures and routine and then make an energy-efficient schedule that matches. What’s even better is that you can adjust 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 provider in Dresden.)

In many instances, hooking up a smart home thermostat with the assistance of McFadden Heating & Cooling is an uncomplicated job if you have a new house. 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 figure out the process so you can pick the proper 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 run on 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 have this wire, your new thermostat could cause your heating and cooling system to have malfunctions.

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

  1. Cut 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 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 almost there. Ensure the C wire isn’t rolled up inside 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 install a smart thermostat with an adaptor designed 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 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 may be a match for your home.

Nest says its thermostats are made to need minimal power and can typically share it with your home comfort system. However, you may need to have a pro like McFadden Heating & Cooling add a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re having power problems or a battery that’s always drained.

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

Rely on McFadden Heating & Cooling for Your Smart Thermostat Installation Needs

At McFadden Heating & Cooling, we’re always on the lookout for ways to keep you more comfortable while keeping utility expenses low. If you want to learn more about switching to a smart thermostat without a C wire, reach us at 1-866-781-0111. We can help you select the right model for your house and even put in new wiring if necessary.