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

June 09, 2021

When you’re seeking methods to reduce heating and cooling costs, installing a smart thermostat is an intelligent idea. These devices adjust to the temperatures you like and routine and then create an energy-efficient schedule that matches. What’s even better is that you can adjust and monitor 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 Franklin.)

In most instances, hooking up a smart home thermostat with the support of Winters Heating and Cooling is a simple process if you have a new house. 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 correct thermostat and enjoy energy savings for a long time.

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

The majority of programmable thermostats run on batteries. When you’re making the move to a smart thermostat, you’ll find that many require a C wire, or common wire, for power. If you don’t use this wire, your new thermostat could cause your heating and cooling system to have malfunctions.

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

  1. Switch 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 you need 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. Ensure the C wire isn’t hidden in the wall. If you can’t find one, we may be able to add one for you or you may be able to run your new thermostat without one.
  5. If you have two thick wires, you may be able to use 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 isn’t right 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 might be a fit for your home.

Nest says its thermostats are made to require not a lot of power and can typically share it with your heating and cooling system. However, you may need to have a pro like Winters Heating and Cooling add a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re running into power problems or a battery that’s constantly 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.

Rely on Winters Heating and Cooling for Your Smart Thermostat Installation Needs

At Winters Heating and Cooling, we’re always seeking approaches to keep you comfier while keeping energy bills inexpensive. If you want to learn more about switching to a smart thermostat without a C wire, contact us at 317-406-5783. We can help you pick the right model for your home and even add new wiring if needed.