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

June 09, 2021

When you’re wanting ways to lower energy expenses, installing a smart thermostat is a smart idea. These devices learn the temperatures you like and routine and then make an energy-efficient schedule to match. What’s even better is that you can adjust and monitor your settings from almost anywhere with your phone, whether you’re lying in bed or on the go. (You might even be eligible for a free smart thermostat depending on rebate programs from your utility provider in Logan.)

In many instances, adding a smart home thermostat with the support of Western Mechanical, Inc. is a simple job if you have a new house. But what if your home 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 select the ideal 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 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 find the wiring.
  3. If there are five or six multicolored wires, you have what’s required for a smart thermostat. You might be thinking 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 close. Ensure the C wire isn’t tucked inside 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 run a smart thermostat with an adaptor specifically for high-voltage systems. Or you may be able to use 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 top brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats might be a fit for you.

Nest says its thermostats are designed to need very little power and can frequently share it with your heating and cooling system. However, you may need to have a professional like Western Mechanical, Inc. 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 includes a C wire adaptor. So, you’re taken care of if you don’t have a thermostat C wire.

Depend on Western Mechanical, Inc. for Your Smart Thermostat Installation Needs

At Western Mechanical, Inc., we’re always on the lookout for ways to keep you more comfortable while keeping utility costs inexpensive. If you want to learn more about installing a smart thermostat without a C wire, reach us at 435-753-5515. We can help you pick the right model for your residence and even add new wiring if necessary.