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 lower heating and cooling bills, getting a smart thermostat is a smart decision. These devices pick up on your favorite temperatures and routine and then create an energy-efficient schedule to match. What’s even better is that you can adjust and watch your settings from nearly anywhere with your phone, whether you’re relaxing in bed or away from home. (You might even be able to get a free smart thermostat depending on rebate programs from your utility company in Port St. Lucie.)

Most of the time, adding a smart home thermostat with the support of Custom Air Systems Inc is a simple job if you have a new residence. But what if your house is older or doesn’t have the right wiring? Can you still have a smart thermostat without C wire? We’ll help you demystify the process so you can pick the correct thermostat and get energy savings for many years.

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 discover 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 determine 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 thinking 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 nearly there. Check the C wire isn’t hidden within the wall. If you can’t find one, we may be able to put in 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 install new wiring.

Do Nest or ecobee Need a C Wire?

Two of the best-selling brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats might be an option for your home.

Nest says its thermostats are created to consume very little power and can frequently share it with your home comfort system. However, you may need to have a pro like Custom Air Systems Inc install a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re having power problems or a battery that’s always drained.

ecobee works 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 Custom Air Systems Inc for Your Smart Thermostat Installation Needs

At Custom Air Systems Inc, we’re always looking for approaches to keep you more comfortable while keeping heating and cooling costs low. If you have questions about switching to a smart thermostat without a C wire, give us a call at 772-247-2283. We can help you select the right model for your home and even add new wiring if needed.