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

June 09, 2021

When you’re seeking methods to reduce energy costs, getting a smart thermostat is a wise decision. These devices pick up on your temperature preferences and routine and then develop an energy-efficient schedule that matches. What’s even better is that you can change and keep an eye on your settings from almost anywhere with your phone, whether you’re lying in bed or out and about. (You might even be able to receive a free smart thermostat depending on rebate programs from your utility supplier in Mankato area.)

Most of the time, adding a smart home thermostat with the help of Northern Comfort Inc is a simple job if you have a new home. But what if your house is older or doesn’t have the correct wiring? Can you still install a smart thermostat without C wire? We’ll help you figure out the process so you can pick the recommended thermostat and get energy savings for a long time.

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

Many programmable thermostats use 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 have this wire, your new thermostat could cause your heating and cooling system to malfunction.

You can determine 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’s needed for a smart thermostat. You might be thinking 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. Make sure the C wire isn’t tucked inside the wall. If you can’t find one, we may be able to put in 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 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 might be a match for you.

Nest says its thermostats are created to require minimal power and can typically share it with your HVAC system. However, you may need to have a pro like Northern Comfort Inc 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 includes a C wire adaptor. So, you’re good if you don’t have a thermostat C wire.

Depend on Northern Comfort Inc for Your Smart Thermostat Installation Needs

At Northern Comfort Inc, we’re always looking for methods to keep you comfier while keeping heating and cooling bills low. If you have questions about installing a smart thermostat without a C wire, contact us at 507-387-6596. We can help you pick the right model for your residence and even add new wiring if necessary.