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

June 09, 2021

When you’re seeking approaches to reduce utility bills, installing a smart thermostat is a smart move. These devices adjust to the temperatures you like and routine and then develop an energy-efficient schedule to match. What’s even better is that you can regulate and monitor your settings from almost anywhere with your phone, whether you’re sitting in bed or out and about. (You might even be able to get a free smart thermostat depending on rebate programs from your utility supplier in Mount Hope.)

In many instances, installing a smart home thermostat with the support of Appalachian Heating is a simple process if you have a newer residence. But what if your residence 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 pick the ideal thermostat and get energy savings for years to come.

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

The majority of programmable thermostats need batteries. When you’re switching to a smart thermostat, you’ll learn that many need a C wire, or common wire, for power. Without this wire, your new thermostat could 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. Pull off 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 pondering what color is the C wire on a thermostat—and the answer to that is typically blue.
  4. If there are three or four thin multicolored wires, you’re almost there. Make sure the C wire isn’t rolled up 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 use 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 won’t work 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 could be a match for you.

Nest says its thermostats are made to require very little power and can often share it with your HVAC system. However, you may need to have a specialist like Appalachian Heating 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 frequently drained.

ecobee connects 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 Appalachian Heating for Your Smart Thermostat Installation Needs

At Appalachian Heating, we’re always seeking methods to keep you more comfortable while keeping energy expenses low. If you have questions about upgrading to a smart thermostat without a C wire, reach us at 304-707-0600. We can help you choose the right model for your residence and even install new wiring if necessary.