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

June 09, 2021

When you’re looking for ways to decrease heating and cooling bills, upgrading to 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 fits. What’s even better is that you can change and watch your settings from nearly anywhere with your phone, whether you’re lying in bed or on the go. (You might even be able to get a free smart thermostat depending on rebate programs from your utility supplier in Plover.)

In most instances, hooking up a smart home thermostat with the support of Point Heating & Cooling is an uncomplicated job if you have a newer house. But what if your home is older or doesn’t have the proper wiring? Can you still install a smart thermostat without C wire? We’ll help you demystify the process so you can choose the correct thermostat and receive energy savings for years to come.

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

Most programmable thermostats run on batteries. When you’re making the move to a smart thermostat, you’ll learn that many require a C wire, or common wire, for power. Without this wire, your new thermostat may cause your heating and cooling system to have malfunctions.

You can determine 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 check the wiring.
  3. If there are five or six multicolored wires, you have what’s required 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. Check the C wire isn’t tucked in 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 use 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 put in 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 might be a match for your needs.

Nest says its thermostats are created to need minimal power and can often share it with your home comfort system. However, you may need to have a specialist like Point Heating & Cooling put in 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 works with 24-volt systems (ones with three to six thermostat wires) and has a C wire adaptor. So, you’re covered if you don’t have a thermostat C wire.

Trust Point Heating & Cooling for Your Smart Thermostat Installation Needs

At Point Heating & Cooling, we’re always seeking approaches to keep you cozier while keeping energy costs inexpensive. If you want to learn more about installing a smart thermostat without a C wire, give us a call at 715-504-0533. We can help you choose the right model for your home and even add new wiring if necessary.