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

June 09, 2021

When you’re wanting ways to decrease utility expenses, installing a smart thermostat is a smart idea. These devices adjust to the temperatures you like and routine and then create an energy-efficient schedule that fits. What’s even better is that you can change and keep an eye on your settings from nearly anywhere with your phone, whether you’re lying in bed or out and about. (You might even be able to receive a free smart thermostat depending on rebate programs from your utility company in Montoursville.)

In many instances, adding a smart home thermostat with the help of Airmen HVAC Service is a straightforward job if you have a more modern residence. But what if your home is older or doesn’t have the right wiring? Can you still install a smart thermostat without C wire? We’ll help you navigate the process so you can select the recommended thermostat and enjoy energy savings for many years.

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

Many 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 may 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. Pull off the thermostat and check 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 close. Check the C wire isn’t rolled up inside 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 run a smart thermostat with an adaptor designed 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 could be a match for your needs.

Nest says its thermostats are made to run on minimal power and can frequently share it with your heating and cooling system. However, you may need to have a professional like Airmen HVAC Service 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 is compatible 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.

Depend on Airmen HVAC Service for Your Smart Thermostat Installation Needs

At Airmen HVAC Service, we’re always on the lookout for ways to keep you comfier while keeping energy costs low. If you want to learn more about installing a smart thermostat without a C wire, give us a call at 570-322-3131. We can help you pick the right model for your residence and even put in new wiring if required.