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

June 09, 2021

When you’re looking for methods to decrease energy bills, getting a smart thermostat is a wise decision. These devices adjust to the temperatures you like and routine and then make an energy-efficient schedule to match. What’s even better is that you can regulate and monitor your settings from just about anywhere with your phone, whether you’re sitting in bed or out and about. (You might even be able to receive a free smart thermostat depending on rebate programs from your utility provider in Rochester.)

Most of the time, adding a smart home thermostat with the assistance of Brogan Heating & AC Inc is an uncomplicated process if you have a new residence. 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 pick the recommended 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 switching to a smart thermostat, you’ll learn 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 ascertain if you have a C wire by doing the following:

  1. Cut power to the thermostat at the breaker.
  2. Take off 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 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 close. Ensure 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 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 install 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 top brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats might work for your needs.

Nest says its thermostats are created to run on not a lot of power and can often share it with your home comfort system. However, you may need to have a professional like Brogan Heating & AC Inc put in a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re having power problems or a battery that’s constantly 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.

Rely on Brogan Heating & AC Inc for Your Smart Thermostat Installation Needs

At Brogan Heating & AC Inc, we’re always seeking methods to keep you comfier while keeping energy costs inexpensive. If you have questions about installing a smart thermostat without a C wire, give us a call at 507-218-0088. We can help you select the right model for your home and even put in new wiring if necessary.