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

June 09, 2021

When you’re seeking approaches to decrease utility expenses, installing a smart thermostat is an intelligent idea. These devices adjust to your temperature preferences and routine and then create an energy-efficient schedule that matches. What’s even better is that you can change 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 eligible for a free smart thermostat depending on rebate programs from your utility provider in Auburn.)

Most of the time, hooking up a smart home thermostat with the assistance of Forster Heating is a simple process if you have a more modern 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 demystify the process so you can pick the right thermostat and receive 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 upgrading to a smart thermostat, you’ll learn that many need a C wire, or common wire, for power. If you don’t have this wire, your new thermostat may cause your heating and cooling system to malfunction.

You can ascertain 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 required for a smart thermostat. You might be wondering 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 almost there. Ensure the C wire isn’t hidden in the wall. If you can’t find one, we may be able to install 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 specifically 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 top brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats may be a match for your needs.

Nest says its thermostats are created to need very little power and can typically share it with your home comfort system. However, you may need to have a pro like Forster Heating add 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 connects with 24-volt systems (ones with three to six thermostat wires) and includes a C wire adaptor. So, you’re covered if you don’t have a thermostat C wire.

Trust Forster Heating for Your Smart Thermostat Installation Needs

At Forster Heating, we’re always on the lookout for ways to keep you more comfortable while keeping heating and cooling costs inexpensive. If you want to learn more about switching to a smart thermostat without a C wire, reach us at 530-885-8081. We can help you choose the right model for your home and even install new wiring if needed.