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

June 09, 2021

When you’re wanting methods to reduce heating and cooling bills, installing a smart thermostat is a wise idea. These devices learn your temperature preferences and routine and then make an energy-efficient schedule that matches. What’s even better is that you can change and watch your settings from almost anywhere with your phone, whether you’re lying in bed or away from home. (You might even be able to receive a free smart thermostat depending on rebate programs from your utility company in Gresham.)

Most of the time, hooking up a smart home thermostat with the help of Honke Heating & AC is a simple job if you have a more modern house. 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 choose the correct thermostat and get energy savings for years to come.

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

The majority of programmable thermostats run on batteries. When you’re switching to a smart thermostat, you’ll find that many have to have a C wire, or common wire, for power. If you don’t have this wire, your new thermostat might cause your heating and cooling system to have glitches.

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. Pull off the thermostat and look at 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 typically blue.
  4. If there are three or four thin multicolored wires, you’re nearly there. Ensure the C wire isn’t hidden in the wall. If you can’t find one, we may be able to put in 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 designed 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 is incompatible 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 might work for you.

Nest says its thermostats are designed to require minimal power and can typically share it with your home comfort system. However, you may need to have a specialist like Honke Heating & AC install 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 covered if you don’t have a thermostat C wire.

Rely on Honke Heating & AC for Your Smart Thermostat Installation Needs

At Honke Heating & AC, we’re always looking for ways to keep you more comfortable while keeping energy expenses low. If you want to learn more about installing a smart thermostat without a C wire, give us a call at 503-663-8033. We can help you choose the right model for your residence and even put in new wiring if required.