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

June 09, 2021

When you’re wanting methods to decrease utility costs, installing a smart thermostat is a smart decision. These devices pick up on your temperature preferences and routine and then develop an energy-efficient schedule that fits. What’s even better is that you can regulate and watch your settings from just about anywhere with your phone, whether you’re lying in bed or out and about. (You might even be able to get a free smart thermostat depending on rebate programs from your utility provider in Perry.)

Most of the time, installing a smart home thermostat with the support of Gillman Heating and Air is a straightforward job if you have a more modern residence. 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 navigate the process so you can choose the proper thermostat and get energy savings for years to come.

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

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

You can find out 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 find the wiring.
  3. If there are five or six multicolored wires, you have what you need for a smart thermostat. You might be wondering 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. Make sure 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 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 just 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 is incompatible 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 may be a match for your home.

Nest says its thermostats are created to require minimal power and can typically share it with your home comfort system. However, you may need to have a pro like Gillman Heating and Air add a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re experiencing power problems or a battery that’s frequently drained.

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

Depend on Gillman Heating and Air for Your Smart Thermostat Installation Needs

At Gillman Heating and Air, we’re always looking for approaches to keep you more comfortable while keeping utility expenses inexpensive. If you have questions about switching to a smart thermostat without a C wire, reach us at 478-202-3076. We can help you pick the right model for your residence and even add new wiring if necessary.