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

June 09, 2021

When you’re wanting approaches to decrease energy expenses, upgrading to a smart thermostat is a wise idea. These devices adjust to your temperature preferences and routine and then create an energy-efficient schedule that fits. What’s even better is that you can adjust and watch your settings from just about anywhere with your phone, whether you’re relaxing in bed or on the go. (You might even be able to get a free smart thermostat depending on rebate programs from your utility provider in Monroe.)

In many instances, hooking up a smart home thermostat with the assistance of Lanz Furnace and Fireplace is a straightforward task if you have a newer house. But what if your residence 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 choose the right thermostat and get energy savings for years to come.

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

Most programmable thermostats run on batteries. When you’re upgrading to a smart thermostat, you’ll discover that many require a C wire, or common wire, for power. Without this wire, your new thermostat may cause your heating and cooling system to malfunction.

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. Take off the thermostat and look at the wiring.
  3. If there are five or six multicolored wires, you have what you need for a smart thermostat. You might be pondering what color is the C wire on a thermostat—and the answer to that is usually blue.
  4. If there are three or four thin multicolored wires, you’re almost there. Ensure the C wire isn’t rolled up inside the wall. If you can’t find one, we may be able to install one for you or you may be able to operate your new thermostat without one.
  5. If you have two thick wires, you may be able to install a smart thermostat with an adaptor just for high-voltage systems. Or you may be able to install a battery-powered smart thermostat, like the Lux Geo Wi-Fi Thermostat, if your wiring isn’t right and you don’t want to replace it.

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 could work for your needs.

Nest says its thermostats are made to require not a lot of power and can frequently share it with your home comfort system. However, you may need to have a professional like Lanz Furnace and Fireplace put in a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re experiencing power problems or a battery that’s constantly drained.

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

Rely on Lanz Furnace and Fireplace for Your Smart Thermostat Installation Needs

At Lanz Furnace and Fireplace, we’re always on the lookout for ways to keep you more comfortable while keeping heating and cooling expenses reasonable. If you have questions about switching to a smart thermostat without a C wire, contact us at 608-291-3606. We can help you select the right model for your house and even install new wiring if necessary.