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

June 09, 2021

When you’re seeking approaches to reduce heating and cooling bills, getting a smart thermostat is a smart idea. These devices learn 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 monitor your settings from just about anywhere with your phone, whether you’re lying in bed or on the go. (You might even be eligible for a free smart thermostat depending on rebate programs from your utility supplier in Derby.)

In most instances, hooking up a smart home thermostat with the assistance of Giordanos Heating and Air Conditioning is a straightforward process if you have a new house. But what if your home is older or doesn’t have the proper wiring? Can you still add a smart thermostat without C wire? We’ll help you demystify the process so you can select the proper thermostat and get energy savings for a long time.

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

Most programmable thermostats run on 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 use this wire, your new thermostat may cause your heating and cooling system to have glitches.

You can find out 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 look at the wiring.
  3. If there are five or six multicolored wires, you have what’s needed for a smart thermostat. You might be pondering 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 almost there. 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 operate 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 install 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 most popular brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats could be a fit for you.

Nest says its thermostats are created to run on very little power and can typically share it with your HVAC system. However, you may need to have a specialist like Giordanos Heating and Air Conditioning 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 frequently 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.

Trust Giordanos Heating and Air Conditioning for Your Smart Thermostat Installation Needs

At Giordanos Heating and Air Conditioning, we’re always seeking methods to keep you comfier while keeping heating and cooling bills reasonable. If you want to learn more about switching to a smart thermostat without a C wire, reach us at 203-772-8319. We can help you choose the right model for your home and even put in new wiring if necessary.