I Want a Smart Thermostat but Don't Have a C Wire - What Are My Options?

June 09, 2021

When you’re seeking ways to reduce energy expenses, getting a smart thermostat is an intelligent idea. These devices learn your favorite temperatures and routine and then develop an energy-efficient schedule to match. What’s even better is that you can adjust and keep an eye on your settings from just about anywhere with your phone, whether you’re lying in bed or away from home. (You might even be eligible for a free smart thermostat depending on rebate programs from your utility provider in Marshalltown.)

In most instances, installing a smart home thermostat with the assistance of B & G HVAC is a straightforward job if you have a more modern house. But what if your home is older or doesn’t have the proper wiring? Can you still have a smart thermostat without C wire? We’ll help you figure out the process so you can choose the ideal thermostat and get energy savings for many years.

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

Most programmable thermostats run on batteries. When you’re switching to a smart thermostat, you’ll discover that many require 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 malfunction.

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

  1. Cut 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’s needed for a smart thermostat. You might be wondering 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. Ensure the C wire isn’t rolled up 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 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 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 won’t work and you don’t want to put in 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 may be an option for your needs.

Nest says its thermostats are created to run on very little power and can often share it with your home comfort system. However, you may need to have a pro like B & G HVAC install a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re running into power problems or a battery that’s always drained.

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

Trust B & G HVAC for Your Smart Thermostat Installation Needs

At B & G HVAC, we’re always seeking ways to keep you more comfortable while keeping energy bills inexpensive. If you want to learn more about switching to a smart thermostat without a C wire, contact us at 641-316-3360. We can help you select the right model for your residence and even install new wiring if required.