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

June 09, 2021

When you’re looking for approaches to reduce heating and cooling costs, installing a smart thermostat is a wise idea. These devices pick up on the temperatures you like and routine and then make an energy-efficient schedule to match. What’s even better is that you can regulate and watch your settings from nearly anywhere with your phone, whether you’re sitting in bed or on the go. (You might even be able to get a free smart thermostat depending on rebate programs from your utility company in Excelsior Springs.)

Most of the time, installing a smart home thermostat with the assistance of Colvin's Heating and Cooling is an uncomplicated task if you have a more modern house. But what if your house is older or doesn’t have the correct wiring? Can you still add a smart thermostat without C wire? We’ll help you demystify the process so you can choose the recommended thermostat and enjoy energy savings for many years.

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

Many programmable thermostats run on batteries. When you’re upgrading to a smart thermostat, you’ll discover that many require a C wire, or common wire, for power. If you don’t have this wire, your new thermostat may cause your heating and cooling system to have malfunctions.

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

  1. Turn off 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 pondering what color is the C wire on a thermostat—and the answer to that is usually blue.
  4. If there are three or four thin multicolored wires, you’re nearly there. Check the C wire isn’t tucked in 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 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 isn’t right and you don’t want to replace it.

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 not a lot of power and can often share it with your heating and cooling system. However, you may need to have a specialist like Colvin's Heating and Cooling put in a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re experiencing power problems or a battery that’s constantly drained.

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

Rely on Colvin's Heating and Cooling for Your Smart Thermostat Installation Needs

At Colvin's Heating and Cooling, we’re always looking for ways to keep you more comfortable while keeping heating and cooling costs inexpensive. If you want to know more about installing a smart thermostat without a C wire, give us a call at 816-379-3918. We can help you pick the right model for your residence and even install new wiring if needed.