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

June 09, 2021

When you’re looking for ways to reduce energy costs, installing a smart thermostat is a smart decision. These devices pick up on your favorite temperatures and routine and then develop an energy-efficient schedule to match. What’s even better is that you can adjust and watch your settings from almost 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 company in Des Moines.)

In most instances, hooking up a smart home thermostat with the assistance of Heartland Heating & Cooling is a straightforward process if you have a newer house. But what if your home is older or doesn’t have the correct 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 many years.

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

The majority of programmable thermostats use batteries. When you’re upgrading to a smart thermostat, you’ll discover that many have to have 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 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’s needed 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 nearly there. Check 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 run your new thermostat without one.
  5. If you have two thick wires, you may be able to install a smart thermostat with an adaptor specifically 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 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 could be an option for your home.

Nest says its thermostats are created to run on minimal power and can frequently share it with your HVAC system. However, you may need to have a specialist like Heartland Heating & Cooling 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 frequently drained.

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

Rely on Heartland Heating & Cooling for Your Smart Thermostat Installation Needs

At Heartland Heating & Cooling, we’re always seeking methods to keep you more comfortable while keeping utility expenses low. If you have questions about installing a smart thermostat without a C wire, reach us at 515-344-3579. We can help you select the right model for your house and even put in new wiring if needed.