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

June 09, 2021

When you’re seeking ways to lower utility expenses, installing a smart thermostat is a wise decision. These devices adjust to the temperatures you like and routine and then make an energy-efficient schedule that matches. What’s even better is that you can regulate and monitor your settings from just about anywhere with your phone, whether you’re lying in bed or away from home. (You might even be eligible for a free smart thermostat depending on rebate programs from your utility supplier in Carson City.)

In many instances, adding a smart home thermostat with the support of Anderson Heating & A/C is a straightforward job if you have a newer residence. But what if your home is older or doesn’t have the right wiring? Can you still add a smart thermostat without C wire? We’ll help you demystify the process so you can choose the right thermostat and get energy savings for many years.

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

The majority of programmable thermostats need 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 might 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. Take off the thermostat and check the wiring.
  3. If there are five or six multicolored wires, you have what you need for a smart thermostat. You might be thinking 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 hidden within the wall. If you can’t find one, we may be able to install 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 install a smart thermostat with an adaptor specifically for high-voltage systems. Or you may be able to operate 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 top brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats might be an option 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 Anderson Heating & A/C install 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 connects 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.

Rely on Anderson Heating & A/C for Your Smart Thermostat Installation Needs

At Anderson Heating & A/C, we’re always seeking methods to keep you comfier while keeping utility bills reasonable. If you have questions about installing a smart thermostat without a C wire, give us a call at 775-230-7628. We can help you pick the right model for your house and even put in new wiring if required.